Ferret Steinmetz wrote a great blog post about love languages, and how they can cause conflict in a relationship. If you and your partner speak different love languages — if the way you recognize that someone loves you isn’t the same as the way your partner recognizes that someone loves them — you might end up splitting, each convinced the other doesn’t love them, when actually they’re just showing it differently. If your partner can’t translate your code, you might as well not be communicating at all.
This is good relationship advice, but it’s also an awesome way to add conflict to a romance novel or story, without making one or the other of the characters evil or stupid or the bad guy. Check it out.