Bruising? Help???

Snasy

I'm quite small and I bruise super easily. When me and my boyfriend are having sex he has a tendency to grip my hips really hard. It doesn't really hurt in the moment, but the next morning I'll have bruising all around my hips and I usually try to hide them from him because I know he'll feel awful. It doesn't really bother me that much but the other day my mom saw the marks and now she thinks I'm in an abusive relationship. Help???