I've been with my partner for four years this month, and despite being attracted to him and turned on, I am unable to produce normal lubrication, which for the longest time was in fact extremely copious. This has been going on for about seven months now.
The problem is, I've recently been in sensual situations (no outright sex) with a friend and have been able to get extremely wet, so it's obviously not a 'plumbing' problem . . .

Can anyone explain this to me? It's been very trying in my relationship because my bf feels as if things are entirely his fault, when I do not believe that to be the case.
Thank you!