I Am trying to understand the psychology here

Not an issue of male pride. An issue of very bad advice. A simple question, why should he bother to learn more? He is not a member of the family, he is not her husband or boyfriend. Why should he tell her the background of his proposal. Why does he owe her this explanation for the lack of a better expression?

No offense intended by the question was asked by Janaan for advice. You do him an intellectual dis-service by assuming anything beyond what he told you and offering him advice that will make the situation far more complicated. He appears to be a very decent guy who did the right thing. The girl is being unreasonable. Yet you are telling him to look out for her feelings and her concerns, why?

He has no cultural, social or moral responsibility to do so.