Pregnancy = No Sex

I just don't know what to do anymore. I know most pregnant women have the opposite problem I do but I'm really just looking for someone to give me an encouraging word and let me know I'm not alone in this. My fiancee does not want anything to do with me sexually. Nothing. The last time I had sex was over a month ago and for him it seemed like such a... chore... And before that it was about a month too. It's not the fact that my tummy is too big, because this was an issue even when my tummy was smaller. It doesn't affect how affectionate he is. He still hugs me and cuddles and kisses me... He's just not aroused by me. He said it's not me, it's just stress. Or that he's just tired. Or now it's the excuse that our birth classes have grossed him out to the point where he can't even think about sex. Every time I try to talk about it he just brushes it off and avoids the truth. I just want to know why. He doesn't understand that I cry myself to sleep almost every night over this, that I wake up with terrible anxiety in the morning worrying about the fact that if he's not having sex with me he has to be having it with someone else, that I beat myself up for not being able to keep his interest. I try to tell him this but he just tells me I'm being silly and he loves me and only me and he'll find me sexy even when I'm old and wrinkled... But actions (or lack there of) speak alot louder than words.
I guess most of this is just to vent and hope that someone out there has experienced the same thing...
All of my pregnant friends have said they have the opposite problem - the men in their lives want sex and they have no desire for it - But I only wish I had that problem!
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every guy reacts different i've been told. some guys dont want to do it and other guys cant keep their hands off. i'd say just ask him about it. try different positions maybe it would make him feel beter? hah i seriously have no idea on that one.