Boyfriend Problem? I guess!

When my boyfriend and I have sex he never finishes . Like we can do it 3 or 4 times a day for hours and he never gets off . My boyfriends sister n law told me that my boyfriend had a problem with steroids when he was in high school and he's had drinking problems in the past too and that may have something to do with it but now he's 22 and he just can't get off . I mean he enjoys sex but I would like to know if it's happened to anyone else or just him? It kinda makes me feel bad ... I've gotten to the point I don't enjoy sex because of this . Any advice?