Husband doesn't like sex

I've been married about a year and a half. We have a great marriage and we are very much in love. There is only one thing we disagree about on a regular bases. He doesn't like sex. He thinks it's something that only needs to be done once a month if not every other month. He says that we don't need to have sex to show our love for each other. When we were dating we had sex every now and then but generally he said that he didn't want our relationship to revolve around sex. It makes me feel really unattractive and it demolishes my self esteem. I think that sex is a really important part of marriage for many reasons. I know he isn't gay and as far as I know he doesn't have an psychological issues. 
I don't know what to do about it. It's gotten to the point that when we do have sex i think he is just doing it to prevent an argument. Has anyone else experienced this issue? Does anyone have any advice?