The songstress and actor had been dating since 2016.
ET has also learned that the split was amicable and "it was not dramatic." ET's told "the relationship had just run its course. It's why [Alwyn] hasn't been spotted at any shows." Swift, 33, is currently on her The Eras tour, which heads to Tampa, Florida next week.
It wasn't so long ago when Swift and Alwyn were said to have been in a great place in their relationship. They started dating in late 2016, and a source told ET back in October that they were "doing great" and that their "relationship is super strong."
That update came just hours after Swift dropped her highly anticipated 10th studio album, Midnights, followed by seven additional songs released in her surprise 3am Edition of the album.
When Swift dropped her album, ET meticulously broke down all the lyrics, including the opening track, "Lavender Haze," which Swift confirmed was inspired by her and Alwyn's romance, and the lengths they go to quiet the outside noise.
"I happened on the phrase 'lavender haze' when I was watching Mad Men, and I looked it up because I thought it sounded cool, and it turns out that it's a common phrase used in the '50s where they would just describe being in love," she said at the time. "If you were in the lavender haze that meant you were in that all-encompassing love glow. I thought that was really beautiful."
"I guess, theoretically, when you're in the lavender haze you'll do anything to stay there and not let people bring you down off of that cloud. I think a lot of people have to deal with this now, not just 'public figures,' because we live in the era of social media, and if the world finds out that you're in love with somebody they're going to weigh in on it," Swift added. "Like my relationship for six years, we've had to dodge weird rumors, tabloid stuff and we just ignore it. This song is sort of about the act of ignoring that stuff to protect the real stuff."
For his part, Alwyn, 32, told British Vogue in September 2018 that he's keenly aware fans always want to be in the know when it came to his and Swift's relationship.
"I’m aware people want to know about that side of things," he told the magazine in reference to Swift. "I think we have been successfully very private, and that has now sunk in for people."
Her 2017 track "Gorgeous" off her Reputation album was also about Alwyn. Fans will recall a Swiftie revealed on Tumblr that, during a secret Reputation listening session, the songstress "made us all promise that if anyone made any accusations of who this song is about, we will tell them it is 100 percent about her angel boyfriend of one year. This isn't a secret. She wanted us to tell people."
Alwyn is also credited for the track "Sweet Nothing" on Midnights, but he's listed on the album under the familiar pseudonym, William Bowery. Alwyn previously contributed to Swift's 2020 albums, Folklore and Evermore, on the tracks "Exile," "Betty," "Champagne Problems," "Coney Island" and "Evermore."
Alwyn's secret alias was eventually confirmed by Swift herself in her Disney+ special, Folklore: The Long Pond Studio Sessions. He'd go on to win a GRAMMY in 2021 for his contributions.