what i get from this is that he is not satisfying you sexually, and you are only giving in to his sexual desires out of guilt. do you masturbate? if not you really need to get on that because it will change the way you look at sex. if you do, show your partner what you do to get off, and have him take the lead. once you are satisfied it becomes easier, although still unpleasant at times, for him to get you. sex needs to be a give and take. dont let him monopolize the whole thing. make sure you get what you need.