Is he cheating? or am I just PARANOID?

I don't think he's cheating. I do think you answered your own question. Everyone, females too, need some time away from their partners, friends, family, whatever. It helps to "recharge the batteries" or "destress" or whatever word people use. I know my husband works my last nerve sometimes (and vice versa, haha) and it helps me not want to kill him if I'm not with him every moment of every day. Relax. Part of your paranoia is the pregnancy I'm guessing. Pregnancy makes us females go wacko every now and then. :)