Is it slutty to want to be a part of a three way relationship?

No, it isn't slutty to want to be a part of a threeway. Sometimes it is wise to know the other pieces of threesome to make sure everyone is on the same page. Make sure that no one gets hurt. There is still à chance, someone could develop feelings for someone in the threesome, which it can be figured out within a group discussion or two. If this fails, have the two parties talk. Hopefully, they have come to some sort of compromise. Otherwise, go with random pieces to the threeway. GOOD LUCK!