Yeah, that's another one of those time things. In my experience in this lifestyle, that was the only thing that really showed my wife that I didn't love someone else more than her. That along with constant, and I mean constant reassurance. Make sure your wife knows that it's not a comparison game. Has she read, or done any research on the poly lifestyle? That might help her. Maybe if she came here and asked a few questions. Big thing to remember too, is to put no pressure on her. She'll come around on her own time. That may not be the schedule that you were hoping for, but if you want it to work (and I know that you do) then she's gonna have to work through things on her own.
Live life to the fullest 'cause you never know if you're gonna wake up tomorrow!