Taylor Swift and Calvin Harris secretly collaborated on music together during their relationship. And now, now there is drama.
The two co-wrote "This Is What You Came For," a hit single the Scottish EDM artist performed with Rihanna and released in late April. The couple broke up in late May.
"Taylor Swift wrote 'This Is What You Came For' under the pseudonym Nils Sjoberg," the pop star's rep confirmed to E! News Wednesday.
Music performing rights databases show "This Is What You Came For" was co-written by both "Nils Sjoberg" and Harris, who used his real name--Adam Wiles.
"And she sings on a little bit of it too...Amazing lyric writer and she smashed it as usual. I wrote the music, produced the song, arranged it and cut the vocals though. And initially she wanted it kept secret, hence the pseudonym," Harris tweeted.
"Hurtful to me at this point that her and her team would go so far out of their way to try and make ME look bad at this stage though," he added.
After the single's release, Harris on Ryan Seacrest's radio show "On-Air With Ryan Seacrest" that he and Swift had never spoken about a music collaboration, adding, "I can't see it happening, though."
Swift was hurt by his words, E! News has learned.
"Adam and Swift did get in an argument about this but Adam was very hesitant in working with Swift on music because his past experience with his other girlfriend," a source told E! News exclusively, referring to Rita Ora. "He thinks Taylor is a talented artist but he wanted going forward to keep his relationship and work separate. He apologized if she took anything to heart but has only respected her throughout their relationship."
"This Is What You Came for" debuted on the Billboard Hot 100 Singles chart soon after its release and soon reached No. 4, marking the highest position Harris has ever reached on that chart.
Since her and Harris' split, Swift has moved on with British "Thor" actor Tom Hiddleston. The two seem to be moving fast in their relationship, meeting each other's parents and talking about kids, and recently jetted off to Australia, where he is filming "Thor: Ragnarok."
"I figure if you're happy in your new relationship you should focus on that instead of trying to tear your ex bf down for something to do," Harris tweeted. "I know you're off tour and you need someone new to try and bury like Katy [Perry] ETC but I'm not that guy, sorry. I won't allow it."
"Please focus on the positive aspects of YOUR life because you've earned a great one," he added. "God bless everyone have a beautiful day."
Swift has not responded to Harris' remarks.
Days before the release of "This Is What You Came For," Swift had promoted the track while at Coachella 2016. She posted on Instagram a photo showing her wearing a jacket with the single's cover art. At the time, fans speculated she was merely supporting her beau.
Sample lyrics include "Lightning, this is what you came for / Lightning strikes every time she moves / And everybody's watching her / But she's looking at you, oh, oh" and "We go fast till they can't replay / Who knows why it's gotta be this way / We say nothing more than we need I say 'your place' when we leave."