It really depends, as others have mentioned. For me, it depends on the position. If we do missionary, he can get REALLY deep and it can hurt if he goes really hard, but if I'm lying on my side and he enters me from behind, he can't penetrate as deep so he can go as hard as he wants. Granted, I usually can't take him hard for too long before it starts to get uncomfortable, but I like it when a guy changes up his speed so it works for me.