Good things about threeways

Me and my boyfriend already did a few threeways with different guys and we love it.Having this kid of relationship made us trust each other like we never trusted no one and if at some point we want to try sex with someone else, that's ok, we just invite him to sleep with us and there is no hidden desire between us or cheating.And who try to have sex with us always love it! Even the straight guy that decided to try. (not saying that was because of its but because of the situation)Did you ever have been in this kind of relationship or did you ever tried to join a couple to do sex with?