Why does this happen?

More and more recently, when my SO gets up in the morning to leave for work... Which is like 4:15am I am left alone in our room feeling sad/depressed that he won't be with me all day. We never really had a lot of days off at a time besides weekends... Although this weekend was a 3 day weekend for Labor Day..... I always missed him when he went to work (before I was pregnant) but now I literally feel like half of me is gone and I get upset about it sometimes. I was wondering if it's because I'm pregnant now... (22w4d) This is one of the worst emotional feelings I've gone through. He never leaves on a bad note with me. I just feel lost without him now. Please tell me this is something because I'm pregnant I can't deal with this forever. I'll go crazy...