As far as those friends, I've expressed myself to a certain extent already which he was fine with and acknowledged some of my points. I wouldn't say that I am seriously concerned about them being totally destructive for him, but he is somewhat caught between loyalties over having been friends with them for some time, and some underlying frustration over bad situations that they have been somewhat responsible for leading him into in the past.
The back story is a bit too complicated to explain but he has made some new acquaintances recently who would probably be worth a bit more investment on his part but he's just not trying much. And what I said was something like "so, those people aren't good enough for you then?"...in a context suggesting that he was still hanging out more with the old friends because they're "cooler." Not very nice, I admit. The thing about the old friends that gets me is, this ESFP has made some changes recently which are very commendable and show that he is really trying to improve himself in some key aspects of his life. But, the reaction of the old friends (in my hearing, though not in his) to these changes was like "what an idiot he is! Those changes are going to be really crap for his social life!" So, he won't go to as many wild parties and go out drinking as much as he used to. Is that so bad? That's all they seem to care about. But then, I don't know them well, maybe there is more to them (and his friendships with them) than those attitudes.
We have discussed the INFJ whose feelings I also probably hurt less...but in a way I am more worried about her. She is both sensitive and fragile. I doubt our friendship would suffer long term but I fear any damage I may have done. I have been pondering for a while how I could say something to her about the "drama" without simply hurting her feelings. That's a difficult balancing act for sure. I don't think I made a good start of it, though.
I hate to say it because I love her a lot, but my mum can be somewhat like that too. Not as much as that flatmate, but at least somewhat. And come to think of it, my ex was somewhat like that as well (though we didn't live together and I should probably be glad the relationship wasn't longer than it was!).
Hm, this is making a little more sense now.