Hormonal??

I’m not really sure what’s going on with me. I’m 18 weeks pregnant and I just do not want to be around the baby father. We’re in a stable relationship never had any problems but for some reason I just don’t want to be around him. I don’t want to talk to him see him or be around him. It makes me sad I don’t know why. I feel like crying when I talk to him or see him or get close to him. Has this ever happened to anyone out there? Is there something wrong with me?