Its pathetic. I think people who do that have no morals and I would not be friends with someone like that. If they can do that to their own partner imagine what they can do to you. Clearly they have no conscience.
And I also think that of men who KNOW a woman isn't on contraception and still have unprotected s.ex then jump up and down when she falls pregnant.
However I would not judge someone unless I knew 100% they did it on purpose...as in they told me cause accidents do happen.