<human>: I've noticed my best friend, has been acting differently lately. When she's around her boyfriend, she usually gets quiet and looks down. She's told me he gets jealous when she talks to anyone else, even me. However, she did kind of cheat on him (through text, not physically) so that could be why he's been getting jealous.  I've asked her, and she says everything's fine. I haven't seen him hurt her or say anything to her, he's pretty polite to her, usually, but he's very self conscious and I've noticed since she's been with him she's been less confident and hasn't been eating a lot (her parents know this). I'm biased against him, though, because he and I don't get along. I also have very little experience in relationships at all, and don't know what to look for.

 So, basically,

Can you condense the text into a few key points?
<bot>: my friend's been acting weird, I don't know whether my prejudice against him is affecting my judgement. I have know idea how to go about this sensitive subject.