There are two main angles, well 2 that I care about. Lots of different levels of behaviour within each though.
One is where the guy gets off on it knowing the woman is enjoying the pain / discomfort (and when I say knowing, I mean knowing - not guessing, believing, assuming, inferring or any other shite - knowing because she explicitly told him). This covers all sorts of kinks, including practitioners of BDSM. This also does not necessarily focus on the vagina and penis - in fact very often the vagina and penis are not involved in the pain at all - sometimes not in the sex either. These men are generally good fucks.
The other is where the guy doesn't take the woman's feelings into consideration at all, where he is a small enough human being to think that his dick causing someone pain makes him more virile. These men do tend to focus on the penis - though forcing the woman into positions that do not suit her but make the angle / feel of penetration better or allow him a specific view of something would be another behaviour I would associate with this type of man. These men are not good fucks.