Search Results: meeting a new girl

My best friend used to be with this guy not long ago who would be extremely jealous and sulky even when she talked to other guys. EVERY day, (towards the end), i shit you not, she'd message me about a new fight or problem he had with her. He once even prevented her meeting her PURELY-a-male-friend because he just didn't like how he wanted to meet up with her despite the travelling inconvenience for him.
Basically he's fairly controlling.
And any time they'd fight he'd make her feel guilty about the problem even if that time it was his fault and not hers.

My friend has been in physically abusive relationships before and even then justified them, so this guy seems like a "good guy" to her, which is scary. Just cause he doesn't hit her, he's automatically a "nice guy".

Once she broke up with him because he was overly-protective and clingy, and she needed some space, but somehow he made the situation out to be like "oh baby ill wait for you, come back to me" & "im trying to give you space but I don't know how" as if she was expected to go back to him after some space. When she kissed someone while she was single, he punched the guy she kissed and swore at her and acted like she cheated even though they were broken up. It was like in his mind, he made it out to be that he still owned her.
Her being the easily influenced girl she is, she apologised to him and he kept raging and said "fuck you" to her and everything.
And they broke up finally afterwards and after he kept coming back to her and talking to her and then messaging her how immature she was.
But now she went back to him and apologised. She genuinely thinks she was wrong even though she was single when kissing the other guy, because thats what the ex made her feel. And she says she likes him again now so she'll most likely get back with him.
Help.. whaat tf am i supposed to do?
This is an unhealthy relationship.