Looking for recommendations for a self-help book for my 18 year old son to help him sensitively navigate tricky relationships with girlfriends, friends, future work colleagues etc. Nothing too long and complex, or too American, but easy to dip into. He doesn't have an ASD diagnosis, so I don't want something that is explicitly aimed at that market, but he does need something to help him assess situations, approach them sensitively, and understand why an intuitive approach might not land well.