I'd like to add:
HorriblePoor communication - basically expecting people to read your mind and then punishing them for not doing so. Or always 'forgetting' what was said (by yourself or others) before and then changing your story or taking a different course of action from discussed and agreed upon. Or speaking in a way that is so circuituous and buried in layers of meaning that the other person has no idea what your actual intent was and take you on your face value. Having dated a few INFPs this was a problem with each of them and their ages ranged from early to late 20s.
Y) Bad boundary making and keeping. Moreso that INFPs let undesirable/unwanted advances continue and allow people to latch on to them. This is bad for them but also a source of vexation for the INFPs actual friends, family, and SO.
Sorry if these have already been brought up, I'm coming onto all these threads late!