Hi Fashion Beetle,
From my experience, the sex keeps improving with time but it is important that you take the decision from the beginning of talking about it freely and with complete sincerity. If you don’t like something you should say so, keep exploring yourself and show your partner what you find agreeable and so on. I think the first “non-worked” version of having sex can show if you are naturally compatible and feel each other well physically and intuitively. On the other hand, sex can become great if one gives it a chance, works on it and try to understand the other person.
On the other side, and I don’t want to throw any negative vibes, but from what I see around me, talking to different friends about their experiences, I found that there is almost no relationship that worked out if sex wasn’t good at the beginning, they usually didn’t break especially because of that, but obviously the compatibility wasn’t there in other areas as well, and add to that the lack of pleasure in bed and it was soon over. However, the problem is more complicated if you had reasonable sex at the beginning and somehow got bored after let’s say a couple of years... It’s not really bad, but not exactly exciting. Would you actually leave your partner (whom you love) because of that? I’m going out with a guy for a couple of years and the last time we had a big fight, I caught myself with this consolation : well, if you don’t marry him, you still got a chance of finding more exciting sex with someone else. So, sex can definitely improve, but does the original situation reveal the future. Since then, I’m wondering.