I see some good points in some of the posts here already.
The point Derbylicious made: "What makes you uncomfortable about this other man? Is it just that she has been having an affair with him?" is a good first point for you to REALLY analyze for a variety of reasons. Because this may be the first point you and she will want to sit down and discuss (unemotionally). In an ideal (this case) 3 way relationship everyone has at least mutual respect & understanding for each other. To have that you have to get to know each other pretty well. It may be that you have some information about the other guy that your wife in fact is not aware of. It's been hidden or blinded to from the what we often call NRE (look it up & learn about it). But that may in fact not be the case at all. You may know little about him (other than a first impression) and you need to be able to ask her to tell you more about him including some examples of what he's providing her that you haven't been. Be open to this - don't be defensive. It is what it is.
I think you have to accept your wife's explanation of desiring a way to acquire certain 'missing pieces' that she values in her life as valid. The fact that she's taken the path she has has validated it. Although as Ceoli pointed out, some might hold up some 'ideal' that ALL relationships would include ALL these pieces, reality has spoken that that's unlikely in the vast majority of people unless your desires are extremely simplistic. (not a bad thing - just rare)
As I'm sure you'll hear from a number of people, the progression is not what anyone would WISH, it's not at all uncommon. You're question and concern over whether it's real or only an excuse is kind of a moot issue at this point. What will matter is how you guys proceed forward from this point. Your actions will determine to some degree the 'truthfulness' of it. I feel she does love you as her attempts to find a solution to the quandary illustrate. This CAN bring you even closer and make your relationship deeper & more meaningful as most everyone here will testify too. But that now depends a lot on YOU !
Good luck. We're here to help any way we can.
Last edited by GroundedSpirit; 01-20-2010 at 06:01 PM.