No spark anymore....

I've been with my husband for 8 yrs now and we're pregnant with our first child. He's never been much into sex and seems to get along better with porn. We have fought forever on the subject but never really got anywhere and I've just dropped it. It does still bother me thought because he likes teen porn. Which, on the internet, is highly likely REAL teens. Trust me, I've seen what he watches. But I still will get the bad rap for being uncomfortable with this because porn is a normal man thing. Plus even when he has stopped watching it he still has no interest in sex. It's just who he is. So I figure there is nothing I can do and I've reaped what I've sown. Besides the lack of sex or wanting from him he is a wonderful man. We have a kind and thoughtful relationship. We love each others company and wanted a family together. He's a great provider and we really are best friends. Unfortunately now that I'm pregnant I feel like we're just marriage partners and best friends. Not lovers. That element is completely gone between us. He used to turn me on. We even used to have some pretty hot sex on the rare occasion. He's good in bed! But now I'm noticing I care less and less and I'm starting to worry. Long term....there may not be a way I can be faithful to him. I've asked for an open marriage. He's a no go. We both really don't want a divorce with a child on the way. He has tried therapy and he didn't find it helpful. It's just the crappiest situation I can imagine. What do you do when you are no.longer sexualy attracted to your other half? The person you count on and lean on and make important decisions with? The one you laugh at and want to see and talk to the moment you wake up and the last before you fall asleep. I know I will one day desperately need physical love and that feeling of being wanted in such a way.