Sex is not everything in a relationship, but it is an important part of the relationship. If a couple does not understand each other in bed, even if they love each other very much, this will produce dissatisfaction and frustration that sooner or later, but invariably, will end up affecting the relationship as a whole, with the possibility of ending it forever.
Among the main causes of incompatibility we can find: different sexual tastes or times (different libidos), discordant size of the genitals (too big or too small) that can cause painful or unsatisfactory intercourse, premature ejaculation, among others. Likewise, a couple that only bases its relationship on sex, lacking everything else, love, coexistence, intimacy, understanding, support, solidarity, fidelity, is unlikely to survive. Therefore, there must be a balance.
Now, if you feel that you and your partner are incompatible in some sexual aspect, I recommend that you communicate openly with him/her, without prejudice or recriminations, and talk about the subject. In this conversation, the following questions can be asked: do we want to have sex with the same frequency? Do we like the same things in bed? Am I open to trying things that my partner likes, even if they don't appeal to me? It's not easy, there will be things that will have to be negotiated, just make sure that both parties are satisfied with what has been agreed.
If you need more help, don't hesitate to consult a therapist or sexologist, who will be able, as an impartial and objective party, to give you the necessary tools to improve your sexual relations and, with it, your relationship in general. I always emphasize that when we can't solve something on our own, the best thing we can do is ask for help from someone who is an expert and knowledgeable on the subject. Don't be ashamed, anything you do to save a relationship you want to maintain will be worth it.