I totally agree with Ceoli, here - you have set this thing up in a way that there could only be two outcomes - the one configuration, or total failure. Everyone is under pressure to "make it happen" and nobody likes working when feeling pressured, especially when it comes to romantic feelings about each other.
It's quite possible that your wife doesn't want to move things "to the next step" because she fears what is going to happen, but so what? That means that there is a problem with the next step, not with your wife.
There is so much pressure in this situation, I can feel it all the way from here! You want something with Nikki, your wife isn't comfortable with that yet (or ever), but you are pushing for it to happen in this triad.
Have you thought that this might not be the best for you three? Have you thought that by setting up this "goal" you have caused people to mask their own true feelings about this whole situation, out of fear of what the "next step" might be?
I am also getting the feeling that there are some goods heads of steam built up on the resentment front, and I don't just mean on your part.
Have you shared your posts here and the responses with your wife and/or Nikki? If so, what has been their reaction?
This whole thing sound horrible for everyone involved.
Oh and why is it YOU that has to make a decision in what to do? Aren't the three of you working together to make this work?
Edit to add:
I Just don't know if I have the patience for this.
Based on what you have posted here I would tend to agree with you.
It feels like my Wife is purposely taking her sweet ass time with moving forward because she knows I'm waiting. I think the reason she is moving like a turtle is because she knows I love Nikki and thinks that I will be putting all my time and energy into Nikki instead of her.
Feelings and thoughts on your part - what does SHE say when you discuss it with her?
I'm ready to just call this whole thing off and be single!
I think that if you continue to push the way it sounds like you are pushing, you might not have a choice in this.