Sex is as important to a relationship as those participating in the relationship make it. Like Randy said, it's about finding a good fit.

I think it depends too on how the act of sex is looked at by a particular person. Similar perception is key. If one person sees sex as a way to bond and express their love while the other person only sees sex as a way to vent stress then the difference in meaning is likely to cause friction or mislead feelings.

I think devotion tends to overcome most incompatibilities. If your partner requires something that you don't particularly care for you might be willing to make an exception for them simply because you desire to make them happy. And vise versa. I think most couples can come to terms about their sexual needs with some kind of compromise but like with all things there are thresholds some are unwilling to break.

In my opinion it's best not to judge your self or judge your partner for your differences in the bedroom (if any). If you're not satisfied or if your partner is not satisfied it doesn't mean that one is right while the other is wrong. It just means you want different things. If you can't deal with that incomparability I think it's best to move on.

I think the worse thing you could ever do is feel forced to do something you don't want to do. In that same sense if you feel that something is truly missing in your sexual life that your partner is unable/unwilling to satisfy then you shouldn't feel forced (or guilt tripped) to accept it.

Just make sure you're being fair to your self and to your partner.