Way late to the thread but I've gotta weigh in on this. I don't think this is necessarily from porn, I think it's (in some cases) just a good ol' double standard. Lots of women have trouble getting off without masturbating, and that's not usually treated as being due to porn.

My own partner used to have this issue. In his case, as he told me, it wasn't really about feeling but about the psychological aspect - he'd psych himself out. If he was penetrating he'd start worrying about getting tired and not being able to finish, if being stimulated by a partner he'd start worrying about them getting tired/that he was taking too long/etc. Getting off by hand was just the easiest way, and felt 'safe'.

What solved it for him was simply being in a closer relationship with more communication and the understanding that it's OK if he gets tired or takes a while. I totally understood this because I feel very similarly.

Just another perspective that it's not always about the porn.