Robert Pattinson and his fiancé, FKA Twigs, are allegedly fighting because of Kristen Stewart. According to a report from Life and Style magazine, the "Twilight" actor wants his ex-girlfriend to attend his wedding with the English singer.

"Things were great until they were going over the guest list, and Rob dropped the bomb about Kristen," an insider said.

"[FKA Twigs] said she couldn't believe it and told him absolutely not."

"FKA Twigs was floored and completely insulted by Rob's suggestion to invite Kristen to the wedding," added the insider.

Robert Pattinson's fiancé supposedly got so offended and began fighting with the movie hunk.

"She was flipping out and they got into a huge fight," the source narrated about FKA Twigs' reaction to inviting Kristen Stewart.

The dark-haired actress cheated on Robert Pattinson years ago with her married "Snow Whie and the Huntsman" director, Rupert Sanders.

"Rob thinks FKA Twigs may be overreacting. He definitely put a damper on their wedding plans and now he's desperately trying to resolve the situation."

While Robert Pattinson and his fiancé are allegedly fighting because of Kristen Stewart, the tomboyish actress seems to not even care about the upcoming wedding of her former beau to FKA Twigs.

A report from Daily Mail revealed that Kristen Stewart was recently photographed looking cozy with her rumored new girlfriend, Alicia Cargile.

"[They are] living together and act like an old married couple," an insider claimed.

Radar Online also revealed what Kristen Stewart thinks about Robert Pattinson and his fiancé.

"As far as [ex-boyfriend] Robert Pattinson goes, that is just a joke. Kristen could care less what he does, who he is with, or where he lives," an insider revealed.

"But when Kristen is with Alicia, there are no walls around her. She not only acts like herself, but she is also incredibly genuine because Alicia brings out the best in her."