There was said to be 'no drama' in their break-up, but Calvin Harris now reportedly believes that Taylor Swift cheated on him with Tom Hiddleston while they were still together.
Pictures emerged of the Scottish DJ's ex passionately kissing Brit actor Tom during a beach trip this week, just two weeks after Calvin confirmed he had split from the singer, reported the Daily Mail.
While at the time Calvin insisted the split was amicable, a source has now told E! News that the star feels "betrayed" and believes Taylor may have been cheating with Tom while they were together.
"He is so angry and feels betrayed," the insider claims. "He is convinced that Taylor was cheating with Tom while they were still together."
The 32-year-old Scottish DJ - who split with the songstress late last month - was pictured in camouflage sweatpants and a grey hoodie as he arrived for a workout at a gym in Los Angeles on Wednesday.
Perhaps he was there to blow off a little steam as it was revealed he unfollowed Taylor Swift and deleted all traces of her on social media. The 26-year-old Shake It Off hitmaker also deleted snaps of them together, but still follows him.
Meanwhile, another source has claimed to The Sun that Calvin was blindsided by the news of Taylor and Tom, and allegedly didn't know for sure anything was going on until just hours before the photos were published on Wednesday.
Calvin seemed to suspiciously Tweet and then delete a social media post that read: "Oh boy it's about to go down" on Wednesday at 2pm, according to Pop Crave and The Sun.
The outing came as photos emerged showing Taylor, 26, enjoying a romantic outing with British actor Tom Hiddleston, 35 almost three weeks after her split with the producer.
In pictures obtained by The Sun, the Blank Space hitmaker kisses and cuddles up to The Night Manager star on a windswept beach on Tuesday.
They were seen locking lips and taking selfies during the outing on Misquamicut beach, near Taylor's Rhode Island mansion.
The secret romance has reportedly been blossoming since the duo hit it off and danced together at the Met Gala on May 9.
A source told MailOnline: "Tom wasted no time in asking Taylor out after he learned she was single. They were texting quite a bit and he asked her out."
Reveal magazine also wrote: "Tom has had the hots for Taylor since the Met Gala. When he learned she was single, he texted her loads and even sent her flowers.
"It was so charming and really put a smile on her face."
No doubt the news came as a blow to Calvin - the pair were last pictured together on May 20, enjoying a passionate kiss.
The EDM producer had suspicions that something was going on with Taylor before these pictures had surfaced, according to a Wednesday report from TMZ.
Insiders for the gossip site say that the two were in a "committed" relationship but Calvin had suspected something a month before their break-up.
The source added about Calvin: "He's pissed and feels betrayed by her."
On Wednesday it was revealed that Calvin has now unfollowed his former girlfriend on Twitter and even took things a step further by blocking her fans from his page.
He also deleted his June 2 tweet in which he confirmed their amicable breakup.
The post read "The only truth here is that a relationship came to an end & what remains is a huge amount of love and respect."
It was later revealed that both Calvin and Taylor have deleted all traces of each other on their social media.
The How Deep is Your Love hitmaker also unfollowed Taylor's brother Austin.
Taylor and Calvin dated for 15 months before announcing the split.