threesomes????

I’m 20 and my boyfriend is 25, and he really wants to try a threesome with me. He’s done them before but wants me to try it out because of how much he loved it when he did it. I’m super interested in trying a threesome, but only with my bf and another guy. He’s expressed to me that he also wants to try it with another girl, but for some reason I get a weird feeling about him with another girl, even if I’m involved too. We talked about it and he said it’s fine and he doesn’t want to pressure me about it (which is exactly why I love him so much) but at the same time I know it’s something he really wants to experience with me.

Am I being weird for acting kind of jealous? Is it unfair of me to be okay with adding another guy and not a girl? Is getting jealous about this kind of thing normal or am I being crazy and selfish?? Please help!!