So he never gets on top and when he does he back cramps? How old is this guy? If he doesn't have some sort of medical problem or is up there in age there is no excuse for not being on top. When you initially said "work" I thought you meant above and beyond, but simply getting on top?!?!? Performing oral sex used to give me a cramp in my tongue, jaw, and neck, but guess what? I did it anyway because I made her orgasm HARD every time. Eventually those muscles got used to the motions and length of time I went down on my woman and there is now no problem. Technique learned from being willing to try helped too. This guy does sound lazy to me if I am reading the situation correctly.