When it comes to long-lasting love, relationships formed in Hollywood don't always have the best track record.
As the years have passed even some of the most solid-seeming pairings have fizzled, blindsiding the fans who found themselves wholly invested.
And in 2019, there was no shortage of surprising splits leaving us scrambling for details.
Arguably the most gripping – with twists and turns almost daily, rebound flings aplenty and a live stage on social media – was Miley Cyrus and Liam Hemsworth's break-up less than a year after their wedding.
• Liam Hemsworth breaks silence over Miley Cyrus split
• Liam Hemsworth and Miley Cyrus' awkward post-split set-up
• Miley Cyrus lashes out at Liam Hemsworth on Instagram
• How Miley Cyrus and Liam Hemsworth's amicable split turned so ugly
In the middle of August, reps for Cyrus confirmed the newlyweds were no longer together, and a day later, the singer was spotted kissing Kaitynn Carter in Italy – Carter fresh out of a relationship with The Hills star Brody Jenner herself.
It was later reported that Hemsworth wasn't aware their separation had been made public until he saw the announcement from Cyrus' spokesperson on social media himself, followed closely by the heavy PDA between Cyrus and Carter, who briefly dated in the weeks following the split.
Eventually, Carter and Cyrus went their separate ways, and Cyrus has since struck up a relationship with Aussie musician Cody Simpson, having known him for years.
Hemsworth has also moved on with Australian actress Maddison Brown, who starred in Netflix drama Dynasty – though they are keeping things low-key.
Cyrus and Simpson, on the other hand, have made their love known, posting raunchy photos together on Instagram, and gushing over each other in interviews.
Cyrus and Hemsworth met and started dating back in 2009, on the set of Nicholas Sparks film The Last Song.
They split for two years in 2013, reuniting in January 2016 to the delight of fans. They wed just before Christmas in 2018.
Theirs was just one of many celebrity splits this year – some surprising, some bizarre, and some very, very expensive.
Here's our list of the most shocking break ups of 2019.
Bradley Cooper and Irina Shayk
Bradley Cooper and Irina Shayk's split came after months of speculation surrounding his strikingly close bond – and strong shipping from fans – with A Star Is Born co-star Lady Gaga.
Romance rumours between the pair were rife – even more so when Gaga called off her engagement to partner Christian Carino.
But when Cooper and Shayk ultimately announced their break-up in June after four years together and a daughter, the rumours were shut down.
According to People, Cooper and Shayk are reportedly working out how to share custody of their daughter Lea De Seine, who they welcomed in March last year.
Their relationship was reportedly on the rocks for months, with reports from The Sun that the couple were living separately.
Shayk was understood to have moved out of Cooper's $US6.55 million ($A9.5 million) Pacific Palisades house with their two-year-old daughter.
A source close to the couple told The Sun: "Things are cooling off between Bradley and Irina in a big way.
"They haven't been good for a few months and Irina decided it would be best if she moved into her own place."
Lady Gaga and Christian Carino
Gaga and Carino revealed in February that they'd called off their engagement after two years of dating.
Weeks later, the singer performed a steamy rendition of Shallowwith Bradley Cooper at the Oscars, in what many fans saw as a sign of something more than friendship between them.
They've long maintained, however, that it was all part of the act – punctuating the romance between their characters Jackson and Ally in A Star Is Born.
Speaking of Gaga's split from Carino, a source told People: "It just didn't work out. Relationships sometimes end.
"There's no long dramatic story."
Gaga, 32, and Carino, 49, began dating in early 2017. She was previously engaged to actor Taylor Kinney.
Adele and Simon Konecki
Music superstar Adele's reps confirmed she separated from her charity boss husband Simon Konecki in April this year, after years of rumours the pair's marriage was on the rocks.
"Adele and her partner have separated," the star's spokesman confirmed. "They are committed to raising their son together lovingly.
"As always, they ask for privacy. There will be no further comment."
It came after swirling rumours that the pair were living separate lives.
"This is a very sad situation — Adele and Simon had been living separate lives for some time," a source told The Sun.
"It was well known among their friends that this time they simply were not going to sort it out. They had been trying for years but eventually you have to accept that something just isn't going to work."
The Hello singer met Konecki after the pair were allegedly introduced by mutual pal Ed Sheeran in 2011 and were first spotted together in January 2012.
Their son, Angelo, was born later that year.
Khloe Kardashian and Tristan Thompson
In one of the most dramatic and tumultuous splits of the year, Khloe Kardashian broke up with her on-off boyfriend Tristan Thompson, the father of her daughter True, after he kissed close friend of the family, Jordyn Woods.
TMZ initially reported that NBA star Thompson hooked up with Woods, the best friend of Khloe's half-sister Kylie Jenner, after partying together in LA into the early hours, prompting Khloe to finally end their relationship.
Woods – who starred on Kylie's spin-off reality series Life of Kylie – later appeared on Jada Pinkett Smith's chat show Red Table Talk addressing the incident.
It also played out heavily on season 16 of Keeping Up With the Kardashians.
It wasn't the first time Thompson had been accused of cheating.
He was captured on camera "motor-boating" a woman in a Washington bar and was seen entering a New York hotel with another woman while Khloe was nine months' pregnant in April 2018.
Khloe and Thompson were first spotted together in 2016, and share their one-year-old daughter, True.
In early December, whispers emerged that the couple had reunited.
Chelsie McCleod and Matt Agnew
From international reality TV royalty to local reality stars, The Bachelor couple Matt Agnew and Chelsie McLeod also called it quits this year, just a few months after they met on the show.
To the disappointment of fans, the pair announced their shock split – just weeks after the finale of the dating show aired – in separate posts on their Instagram pages.
Agnew said the six month's since filming ended had been a "very unique experience" but said their relationship didn't "translate" into the outside world.
"Chels and I have made some beautiful memories together that I'll always cherish, and I wish her nothing but the absolute best," he wrote.
"However, it's with a heavy heart that I write this. For Chels and me, our relationship hasn't translated from filming to the real, every day world as we had hoped."
He described McLeod as a "very special woman" and hoped she would find the "happiness she deserves".
The astrophysicist added that there was no other romantic interest in his life at the moment, pre-empting the inevitable speculation that he had decided to pursue runner-up Abbie Chatfield, with whom he had a "strong physical connection" as he put it on the show.
"For those who may wonder if there's someone else for me right now, there absolutely is not," he said.
"It's no one's fault, it's just life."
McLeod took to her own Instagram to share multiple pictures of her and Agnew throughout the show while also thanking everyone for their "support and kind words".
She reminded her followers to be kind to others online as they "don't know what is going on behind the screen".
Abbie Chatfield was also compelled to comment, asking people to stop involving her in the situation.
Brody Jenner and Kaitlynn Carter
The Hills: New Beginnings couple Brody Jenner and Kaitlynn Carter also headed to splitsville in August this year — but they haven't had to work out a divorce settlement because they were never really married in the first place.
The couple had an elaborate wedding in Bali in June 2018 but a source close to the duo confirmed to Page Six that the union wasn't legal.
The source said they had been separated for a while, Kaitlynn having moved out of the Malibu house they shared well before their break up was made public.
A few weeks later, she was pictured kissing freshly-single Miley Cyrus on a holiday in Italy, sparking a short fling between the pair.
Carter later penned an emotional essay for Elle about her relationship with Cyrus, which ended in September, stating that she "never thought she was even capable of loving a woman the way (she) loved (Cyrus)".
"Reflecting back on our three-year friendship, I realised I'd always been drawn to her in a way I wasn't with other friends, but until that trip it had never crossed my mind to think of her in a romantic sense," she added.
Katie Holmes and Jamie Foxx
News of notoriously private couple Katie Holmes and Jamie Foxx's split also emerged in August, seemingly the month of high-profile breakups.
However, the six-year relationship between the A-listers actually ended in May.
After pictures emerged showing the Oscar winner partying in Los Angeles with much-younger singer Sela Vave, news outlets speculated Foxx, 51, was cheating on Holmes, 40.
But a spy at New York restaurant La Esquina overheard the actress — who was having dinner with girlfriends — tell a pal, "What Jamie does is his business, we haven't been together for months."
They'd been together since 2013 — about a year after Holmes divorced Tom Cruise. The pair were highly secretive about their early trysts, meeting up late at night at hotels and sneaking out back entrances to avoid a spotlight on their romance.
Mackenzie and Jeff Bezos
The Amazon CEO and former "world's richest man" Jeff Bezos and his wife Mackenzie announced via Twitter on January 9 that they were divorcing.
"We feel incredibly lucky to have found each other and deeply grateful for every one of the years we have been married to each other," the couple, who have four children together, said in a statement posted to Jeff's Twitter account.
"If we had known we would separate after 25 years, we would do it all again."
According to the statement, the couple went through a "long period of loving exploration and trial separation" before deciding to divorce.
Jeff is currently dating former TV anchor Lauren Sanchez, while MacKenzie is now the 22nd richest person in the world thanks to a $US 55 billion divorce settlement.
It was later reported that Mackenzie pledged half her overnight fortune to charity.
Travis Scott and Kylie Jenner
The makeup mogul, 22, made the announcement on Twitter in October following a report claiming that she and ex-boyfriend Tyga were spotted together amid buzz that she'd split from Scott.
"The internet makes everything 100 times more dramatic than what it really is. There was no '2am date with Tyga'. You see me drop two of my friends off at a studio that he happened to be at," she tweeted Thursday morning.
"Travis and i are on great terms and our main focus right now is Stormi ‼ our friendship and our daughter is priority (sic)."
Jenner and the Sicko Mode rapper, 28, reportedly split after going through a cooling-off period for several weeks.
The former couple raised flags when Jenner attended Justin Bieber and Hailey Baldwin's second wedding in South Carolina without Scott by her side.
Instead, she brought their 20-month-old daughter, Stormi, as her plus-one.
They had been together for two years.
Avril Lavinge and Phillip Sarofim
It was splitsville for Avril Lavigne and her billionaire boyfriend in December, with the pair calling it quits on their relationship after two years.
Lavigne, 35, was first linked to Phillip Sarofim, the son of Texas billionaire investor Fayez Sarofim, after the two were spotted on a dinner date in Los Angeles in March 2018.
They reportedly met through mutual friends and had already been an item for a few months at the time, according to People magazine.
They were last seen together in June when the former couple stepped out for a day of shopping in West Hollywood.
Lavigne was previously married to Nickelback singer Chad Kroeger.
Channing Tatum and Jessie J
In late December, sources close to unlikely celebrity couple Jessie J and Channing Tatum confirmed the couple had split after dating for just over a year.
The pair are said to have ended their romance in November, according to Us Weekly.
According to an insider, the two are still amicable, with the source explaining to The Sun: "Channing and Jessie broke up about a month ago.
"They are still really close and still good friends."
The 31-year-old British singer and 39-year-old Magic Mike hunk were first linked in October last year.
They were said to have been dating for a few months already at the time, with Channing splitting from wife Jenna Dewan in April 2018.
The Hollywood actor shares six-year-old Everly with his ex, and Jenna previously admitted she felt "blindsided" by how quickly he had moved on.