How do you deal with a man that's only interested in sex if he's in the mood?

My SO likes to have sex when he likes to have sex. When I'm in the mood (which is almost always) there are times he isn't...so I get no sex. Yet when he's in the mood, I'm always available and ready. I feel like the sex is only about him and he doesn't care to fulfill my needs. It's starting to effect our relationship. Any insight?

I'm not trying to force him to have sex if he doesn't want to but I feel like a relationship is about give and take. He's taking when he wants it but hardly ever giving when I do. Shouldn't we both be pleased sexually? Or is sex only for the male

If I was to go else where to get my needs met I would be wrong yet one may say he isn't obligated to please me...