I think as well, if you asked most guys the type of woman they would hope to avoid getting pregnant or getting married to it would be Keiko. She has far more unlikable attributes than likable ones. It seems Miles is on constant damage limitation mode with her trying to avoid upsetting her.
I almost get the feeling he was intimidated by her and it was pretty clear who wore the trousers in their relationship. Not to be blunt but by most people's standards Keiko would be classed as a b****.