Contrary to what many of us would like to believe, sexual compatibility doesn't just happen naturally—it takes time and deliberate effort. Because sexual desires and expectations are highly personal, even if you and your partner have a lot in common, you're going to have some differences.
Could you imagine having to eat the exact same food, in the exact same quantity, at the exact same time as your partner for the rest of your lives? It would be impossible, not to mention unhealthy and incredibly boring—your bodies are different! However, for some reason, we expect our sex lives to fall into place effortlessly, and when it doesn't happen, we feel let down.