Why won't he apologize?

Answer 1

You're only going to get an answer to your question, by talking to this person, whoever he is.

This situation frequently occurs, because the person you expect to apologise, does know or realise, that such an apology is needed. That some action or words, have caused offence. People are not mind-readers, so don't expect them to be.

For the sake of any future relationship, whatever form that may be. You clearly need to talk this out, to prevent future misunderstandings.