This is a response to volume 4, John Card Number 5 ("Love and Marriage")...
I don't know that gender differences complicate things more or less after marriage. I think that the primary communication problem with married couples is believing that you know each other well enough to make assumptions about how the other is feeling or what the other is thinking or what the other means when he/she says something. This is probably one of the reasons many married people believe that their spouse is taking them for granted.
I don't know that the question of whether "he/she is the one" is settled after marriage. Husbands and wives change and grow even after they are married. Married couples can't "relax" in the area of communication. It is important to keep working at maintaining open, honest communication in order to assure that you are aware of the changes and growth in the other and, in the best of all worlds, change and grow together.