Someone's jealous!

Taylor Swift, 25, swears she's never getting back together with former flame Harry Styles, 21, but boyfriend Calvin Harris doesn't believe her. According to a new report, the 31-year-old DJ is worried she still has feelings for the One Direction member.

RELATED: Taylor Swift and Calvin Harris Go on Double Date With Another Famous Couple — Find Out Who!

taylor swift and harry styles

Taylor Swift and Harry Styles in December 2012.

“Calvin has separated himself from his playboy ways and is all in with his relationship with Taylor. He doesn’t like when she mentions her exes," a source told Hollywood Life.

"He wants her to not talk about them, even if it’s her throwing shade at them. He wants her to be totally devoted to him. He gets jealous thinking that she still may have feelings for people like Harry or others she has dated — it’s upsetting to him."

RELATED: Calvin Harris Ready to Pop the Question to Taylor Swift!

This isn't the first time the blonde beauty has been in hot water over a former flame. As Life & Style previously reported, she allegedly texted with Jake Gyllenhaal after he got her number back in June. The duo dated in 2010, but broke up after only two months.

Better watch your back, Calvin!