is he cheating on me?

My husband and I have always been very active. We've never gone 3 days with no sex.... In the past 2 weeks we've had sex once which isn't like him at all, i even tried to seduce him and he just moved my hand away. On the weekends he is always looking for an excuse to leave me. (Those are the only days I get with him) he tends to make plans without including me. I have no friends, or family near me so I'm always stuck at home angry. I'm currently expecting our 1st child together.. 
Last night, he asked me if I had any plans for today. (Ummm wtf? When do I ever make plans, specially for a holiday when he is the only person I have) I said no, why do you? He then told me that he was gonna leave 2 hours away from where we live to go buy a dishwasher for the house out there and to go help his sister figure out how to take a loan out. That he was gonna go spend his day out there , go to the gym, and possibly help his dad out with anything he might need help with. He left super early... and I can't help but have negative thoughts in my head that he is cheating on me. Why hasn't he had sex with me? (He is a horny ass) why is he always avoiding time with me? (Even on a fucking holiday he decides to leave me) I'm so angry and upset.