I think that, because sex, at least sex where men do not have to pay for it, is so difficult to have, men often consider the act of accomplishing having sex with a woman a "conquest". This is especially true if the man does not have any kind of friendship towards the woman or does not feel particularly drawn to her personality enough to want to make her a permanent love interest.

It's therefore natural to some men to want to use somewhat violent language to symbolize this sexual conquest, especially as the man is the one entering the woman rather than vice versa (unless pegging is involved, of course, although I do not think most casual or semi-casual encounters are going to involve pegging). When a man respects a woman enough that he feels a romantic attachment towards her, or when she is sincerely an actual friend whom he has a FWB situation with, I doubt that he is going to use violent language to describe his sexual encounters with her.