moody boyfriend

How do you deal with a moody SO? I feel the past few days mine has just been in a bad mood and he like barely says anything to me. And he was acting like that today to and just snapped at me for something that's not completely my fault. He's just really hard to talk to about feelings and stuff so why I haven't really said anything to him. I just don't know how to handle it. And I'm just super sensitive because I'm pregnant.