Adding a 3rd girl

I’m 18 and my boyfriend is 20, we have wild sex for over 3 years now, and we were wondering what it would be like to add someone into the fun. Just the other day i read an article about having a threesome and I got a little interested. My boyfriend and I have had a few small jealously issues but nothing worth breaking up. I guess my real question here is if we should try it or not? Is it too taboo? I brought it up and we talked about guidelines and we even found a Girl that is interested. Please comment feedback on your true opinions, are the problems that it may cause worth it? Can people have a threesome without any problems what so ever?