Your drives and desires, sexually and otherwise, don't match up, and you feel the tension of this disconnect. Things might be smooth enough between you at first, but as time goes on, you recognize that you assert yourselves very differently. Your struggles for independence within the relationship cause misunderstandings between you; in essence, you're so concerned with your own needs and drives that you aren't able to listen to each other very well, so the needs and drives of your partner fly right over your heads.
Tension and discomfort mount whenever you're together. It's hard to make plans together because you both have a different idea of how things should be done, from the small things -- which route to take to the restaurant -- to the bigger ones. And inevitably, you argue about these issues that come up. Whether you let the argument blow up into a full-blown fight is up to you, but you start to notice a pattern of misfired energies. You might stop in the middle of a heated discussion and realize that neither of you knows what you're fighting about, much less why it matters so much! The way to get over this is to slow down and start listening to each other. To some extent, you have to abandon your own egos in order to do this, which isn't easy; but it's the only way you'll be able to treat each other's needs as being equal to your own.