My boyfriend of 13-years wants me to have a three some with a friend of ours.
The problem is I do too. I've had a crush on this other guy for a long time. This guy is also
Willing to do this.

Why would your boyfriend want to share you and have a 3-some with another guy? Seems kind of weird to me. Another girl I could understand more.

It's sort of up to you, but a lot of the time things will be weird with the friend afterwards and most likely you will lose contact cause there will be an odd feeling every time you both see him. But then again, although this is common it might not necessarily happen.

Also yes, why does he want to do it with another guy?

I have a friend that did the same thing and even know her boyfriend was the one with the idea after she went through with it he was always jealous and thinking she was cheating on him and it just caused a lot of problems! The eventually broke up... plus I would Never want my boyfriend to want to "share" me.

Maybe your boy friend senses your feelings for his friend and has decided to test you.

Why is it boyfriend of 13 years. Isn't that a little long to just be considered a boy friend. I mean by then I'd figure I'd at least get my lover or my man or my partner. Hmm.

Once you cross that line, you will never be able to go back. Your relationship will change, most likely not for the better.