Icelandicman, people are just trying to point out that a 2+1 model of relationship is uneven. You and your wife are the primary relationship, fine, but that means that the unicorn is inherently unequal. If someone agrees to that, great, but there's no point in getting pissed at people who point out that that is indeed the case. Unless you and your wife decide that it is a 1+1+1 relationship where everyone can develop feelings at their own speed without having to worry about everything being exactly the same is acceptable, then there is going to be inequality in there. That's not necessarily a bad thing, it's just the way it is.
There are women out there who will agree to that kind of situation. Good luck finding the one for you, and I hope that you're able to make a very difficult relationship structure work.