I found the old thread about Ross, and this is what one poster had to say about him. Quite long, but she makes some good points!
"He is in love with the same woman for 9yrs before he does anything about it. He can at first be seen as just infatuated, it's even quite sweet. But he's at times angry, jealous, controlling, manipulative etc. All behind a veneer of vulnerability and big gestures. Of course he then gets into a relationship with this woman. He is pretty full on pretty quickly and starts to change. Rude about her job, clingy, controlling, starts becoming paranoid and jealous, turns up at her place of work and makes scenes, deliberately tags along on a work trip and embarrasses her all because of the perceived threat of 'Mark'. The Mark thing escalates, she finally snaps and they agree to a break. They quickly decide that this is the wrong thing and are making pains to sort things out (over the phone) but of course Mark is there, Ross assumes the worst and sleeps with the Xerox girl. From this point onwards, he changes into something I really don't like.
He runs around trying to conceal the fact he slept with another woman. When found out he says he only did it because he thought Rachel was doing the same (it's her fault he had sex with another woman), he is accusatory, refuses to accept responsibility. He goes on in subsequent episodes to tell Carol that the relationship between him and Rachel broke down because she was sleeping with Mark (all her fault again and blatant lies), he continues to refuse to accept responsibility and when Rachel finally tries to move on and explains how important it is to her that he admits what he did (18 PAGES FRONT AND BACK!!!), he falls asleep, lies, sleeps with her again anyway, then throws it all back in her face.
It continues right to the end. He dates Mona, lies to her, lets her down, changes the locks to keep her out, gives mixed messages, humiliates her etc. He develops a hilarious rage issue where he screams in the face of the woman he's telling the lake Tipidabo story to, screams at another woman about her lighting (the one with his white teeth), invites a woman who is vulnerable to his apartment and humiliates her, calls her his girlfriend, mocks her and then sends her away. All the time continuing his controlling attitude towards Rachel by not giving her phone messages, keeping stuff from her, interfering with her work plans yet again by bribing her boss.
He's given these sweet big gestures and shown as needy and vulnerable but really he's controlling and awful. They got it really wrong towards the end."