Not horny anymore

So I’m 22 weeks pregnant and my husband wants to have sex every night at least. I’m just not into it. I don’t mind masturbating but the thought of sex isn’t appealing to me anymore. Lately I’ve been getting horny when I watch him watch porn and jack off (to women) and idk if me being pregnant has turned me bisexual or what

How can I fix this? It’s upsetting him