I'm not quite sure I'm about to make sense but I'll do my best.
My partner has a female friend, met after we did. We've been together 5 years, 2 dc and she came along in year 3.
My dp sees her more than anyone else of his friends and invites her places or goes to see her etc. I've questioned this and he always says she's going through a hard time and needs support and that's why he's so attentive. To me, whether she's going through a hard time or not, it's still his choice to see her so frequently isn't it? It's not like he can't say no?
I've probably left buts out but I'll try and flesh anything out if I have