John Mayer Split Up The Two Taylors!

John Mayer is a notorious Hollywood heart-breaker, but usually his douchey-ness is limited to the ladies -- until now.

OK reports that John, who has been known to flirt with Taylor Swift on Twitter, is the one who came between her and Taylor Lautner.

“John’s dad is telling everyone John has a thing for Swift,” a source says. Adding to the "ick" factor is the fact that John is more than ten years older than the twenty-year-old.

The two dueted on John's new single, "Half of my Heart," and although the source says Swift isn't interested in the older man, it may have caused her to rethink her relationship with her younger guy.

“She could no longer lead him on,” the pal says of Lautner. “She feels she needs someone more mature.”

She was going to wait to deliver Lautner the bad news until after the holidays, but when Taylor gave her diamond earrings for her 20th birthday December 13th, she knew she couldn't lead him on any longer.

“She said she just wants to be friends." Ouch!

But Taylor Lautner isn't giving up so easily. “He’s devastated,” says the source, but he's still “holding out hope” that Taylor will change her mind!