Of course the sex is always more frequent and exciting in the beginning (at least it should be), but talking about what you expect sexually out of a relationship is very important.
Understanding your partner's sex language will show them how attentive you are and it will lead to better intimacy. Learning to be intuitive and understanding intimacy is a skill that most couples don't know they need.
After you settle in with each other, maybe your significant other's sex drive is higher or lower than you want it to be. Maybe you want to try something new, but it isn't their cup of tea.
Some people are delusional enough to think that sex is not an important factor in a relationship. They think that as long as there is some sort of intimacy, other than sex, that their relationship is stronger than most. Don't let these rantings of miserable people fool you. Sex lives matter!
Yes, being with someone that you love should be more than about sex. There are other important aspects of a relationship that should prove fulfilling, but no matter how happy you may claim to be, if sex is lacking then there's a big problem. Personally I feel like if a couple is not having sex, and if they are not sleeping in the same bed together, they might as well be roommates! Before someone starts to complain about how being in love is more important, along with honesty, and trust, and communication, just stop and think. Honesty, trust and communication, and even love are all qualities that most true friends share with one another. If you're truly IN LOVE with your partner, then sex should come naturally, or a great effort needs to be put into making time for sex.
My boyfriend and I have sex often. At least 4 times a week. This has actually dwindled down from 2 times a day everyday, when we first started dating. Obviously the decline is natural, but we make sure to keep up on it. He definitely doesn't mind at all. We naturally gravitate towards each other. The sexual chemistry is strong and it doesn't take much for us to start dancing horizontally, but sometimes we'll look up and realize we haven't had sex in well over a week! I understand that this may not seem drastic to most, but it is to us, and to each his own. We know that sex is important and we love it. I personally get a little more stir crazy when we go days without sex, but given the circumstances of his last relationship....let's just say he has been conditioned to wait for months on end (ouch).
This leads me back into sexpectations. I don't like going more than 4 days without having sex. I have a high libido and I enjoy regular sex. I enjoy the intensity of love making, and the pain of rough wild sex. On the other hand, while by boyfriend is willing to accommodate me, he is more relaxed when it comes to sex. Don't get me wrong. He enjoys it. How could be not. However, referring to earlier, in his last relationship, he had to beg for intimacy. He had to jump through hoops and the whole sexually aspect of his old relationship was very vanilla - no pun intended. It was boring. Having experienced this for years, has conditioned him to be OK with going without sex, but it's also great because he gets so excited by some of the basic things I show him.