She said in April: "I'm just taking things as they come.
"I'm in a magical relationship right now. And of course I want it to be ours, and low key...This is the one thing that's been mine about my personal life."
The musician, who previously dated stars including Jake Gyllenhaal, Harry Styles and Taylor Lautner, admitted the attention on her personal life put her off dating for a long time before she met Harris.
The pair celebrated their one-year anniversary with this themed cake.
She said: "You know, I went out on a normal amount of dates in my early 20s, and I got absolutely slaughtered for it.
"And it took a lot of hard work and altering my decision-making. I didn't date for two and a half years. Should I have had to do that? No."
Ellie Goulding originally set Harris and Swift up when she introduced them at the BRIT Awards afterparty in London in 2015.
She said: "How did I set up Taylor and Calvin? It just kind of happened.
"They're both good people, both dear friends. I thought it might work - and it did.
"Calvin is a really great mate and he's so fantastic, and Taylor is such a cool person who I love. I thought. 'They're both really awesome and both really tall, they'll brilliant together'."
