<human>: Can you condense the text into three sentences or less?

Don't want to get too detailed because I'm not sure if he reddits, but I've been friends with F for several years now, and as long as I know her she's been friends with M (he's sort of an acquaintance; I never chat with him unless I'm with her). She's always been WAY too forgiving of him and way too complacent with him. 

However, recently, due to events (not going to get specific...) they started to kind of circle around the idea of dating, but he wasn't sure that he liked her well enough. She started to move on, he got jealous, and suddenly was a lot nicer to her (though by nicer I mean basic human decency). He was already getting super jealous of F chatting with other guys, even when they weren't dating. 

Recently they made it official and they've started dating, however he's been reverting to his old behaviors (basically he doesn't really show any affection or kindness). He also literally only asked her to be his girlfriend because it would be more convenient for him. It feels like he was (maybe unconsciously) manipulative in getting them into a relationship. This makes me worried. Should I do something? Should I say something? I don't want to jeopardize my friendship with her, but I care a lot about her and I want to make sure she's in a relationship with a good person.
<bot>: Friend is in what I'm worried is a manipulative relationship, or at least a relationship starting out with some emotional manipulation, what do I do?