Giving/receiving head?

So I've been in a long time relationship and of course I go down on him frequently. It doesn't bother me and sometimes I like doing it. But he refuses to go down on me. I feel like I'm missing out and that he should at least TRY since I do it for him. He got down there once but didn't actually do anything. He says it's because vaginas look gross and smell weird. So now along with never having experienced it, I'm self conciliatory about everything down there... What should I do :o