Polyamory???

Blue

My bf and I have talked about adding a third person(woman) to our relationship. I quests you can say Ima little curious. I've had 2 sexual encounters with women before(oral sex). I'm open to trying it. Right now I'm pregnant and he has a child from a previous marriage, he's looking at it as the other person would be added help for us. She could bring more money in and always help with the kids. We've had many discussions about it and both agreed that if one of us didn't like it anymore we'd stop. We are EXTREMELY honest with each other and Levi's tell each other everything. He reassures me how much he's in love with me and never wants to leave me. && that I'll always come first.

So my question is, what the fuck am I so afraid of