Agree with redpepper. Moving in together is too soon. Say it doesn't work out - would you just kick her out? I'd advice you to do some reading on unicorn care.
Also, did I understand it correctly that your bf is not in love with this girl? Jealousy isn't alleviated even if he gets to sleep with her too, if he sees that the two of you have a strong emotional connection he and this other girl don't share. Moving in will make all problems that surface that much more intense. Do you have space for her? Should everyone have their own room? How to split living expenses? Cooking shifts?
Come clean to the bf. Enjoy dating! There is plenty of time to argue over who left the socks in the drier in the future, if the three of you work it out. Also, triads can't be forced. Right now it looks like you are the hinge on a vee, with your bf occasionally being let in on the fun. His emotions well may change when he hears that this isn't just about sex for you.
"Resentment destroys more alcoholics than anything else. From it stems the root of our spiritual disease."
"In dealing with resentments, we set them on paper - list people, institutions and principles with whom you are angry. Ask yourself why you are angry."
"In most cases it was found out that our self-esteem, our pocketbooks, our ambitions, our personal relationships, including sex, were hurt or threatened. We were sore, burnt-up." Alcoholics Anonymous, 64-65.
Last edited by BlackUnicorn; 02-25-2011 at 08:14 PM.