Strange Fantasies ?!!

I am 16 weeks pregnant and my baby daddy and I were FWB since I've gotten pregnant we haven't had sex much as he's scared to hurt baby I was not happy about it but I understood but lately I've been having strange fantasies of watching him with another woman everytime I think about it I get supper turned on. I'm bisexual but never done a three some because I'm usually a very jealous person so it's strange to me why the thought of him with someone else turns me on so much now that I'm pregnant maybe it's the hormones lol. Is it weird?