Being possessive ??

So I am 34 weeks pregnant and I feel so possessive over my SO. He spends a lot of time with his bff and his girlfriend they live fairly close. They have been bffs since they were kids. I don't have a problem with them they are nice to me. But lately I just get so annoyed when he mentions he was over there. I just feel so left out they are always hanging out and I don't ever get invited or anything. His bffs girlfriend is also pregnant and he is so much nicer to her he is not like that with me at all. Maybe  I'm just being a big baby and I should suck it up. I know my SO is getting annoyed with me. I just hate feeling this way idk what to do