Maybe "miffed" is putting it mildly, actually. Kristen Stewart is reportedly really, really angry about that whole FKA Twigs getting engaged to Stewart's former "Twilight" boyfriend, Robert Pattinson — even if Stewart herself may be claiming otherwise. "She is really pissed off over Rob getting engaged to FKA Twigs after knowing her for only a couple of months. She is saying she really does not care at all about this, but everyone knows that is not the case," a source tells  Radar Online. "She really wonders if part of the reason he got involved with FKA Twigs so quickly is to get back at her."

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"Kristen was with Rob for several years and he never gave her the option of marriage," the source adds. "Every time she tried to bring it up, he would always shoot her down and say he was not ready. The fact that he was all of a sudden ready just really annoys her."

And hell hath no fury like an ex-girlfriend annoyed. Or something. 

Follow Ned Ehrbar on Twitter: @nedrick