In many couples, one or both partners feel that the other doesn't understand how to satisfy them sexually. And I know from my work at a sex and relationships counsellor that this can knock the confidence of both people.
The problem is that when it comes to sex we expect to be instant experts, with instinctive knowledge of what pleases us and a partner. But actually, sex is just like any other skill. If we want to learn how to drive a car or ride a bike, we have to start as beginners and take lessons. And with sex, to understand your own responses and your lover's, you have to learn and practice.
This is because everyone responds differently to sex and sexual arousal. Some like gentle touches, others prefer heavier, rougher contact. One person will be turned on by something another finds unpleasant or uninteresting. Unless you're psychic, the only way to get to know your partner's tastes, and for them to get to know yours, is by communicating.