That is very strange that he was in an asexual relationship for FIFTEEN years? Who accepts that? Unless it's someone else who is asexual? This all sounds very strange to me, and I wonder why you're accepting of this girlfriend/non-girlfriend status? Why not just confront him, tell him it's not fair to you to act like he's your boyfriend and tell people he's not. Does he want a relationship with you or not? Bottom line. Cut to the chase!