I recently had the same problem. Me and my boyfriend have been living with each other for 5 months and have had a great sex life. Except for sometimes he can last up to 40 minutes and then just end up masterbating to finish. That usually makes me think im not good enough for hes not attracted to me. About a week ago i woke up to the bed moving and i though he was masterbating in the middle of the night but i wouldnt let myself believe that so i just tried to fall back asleep. We didnt have sleep all week so it was starting to concern me. Last night i woke up to the same thing about 4 times in the middle of the night! Each time i would roll over and he would stop cause he though i was awake i guess. But then he would do it again like an hour later!! Am i not supposed to think thats strange or hes not attracted to me? I alway ask him to have sex every night and he says he is too tired now. I never say no to sex so i dont know why hes opting to masterbate in the middle of the night now.