I am confused about the logistics. Why aren't they living together? I can see her point, but I think you have a point too...What does a full partner mean to you?
Does in mean that you want to live with him?
Where I am confused, and I might be dense! is if SHE doesn't live with him, why does she mind if you want to? Is she worried about an emotional disconnect from him? Is she worried about coming to visit and having you there? Why does she "need to move" if you want to live with him? Do all three of you need to co-habitat?
I don't like the words primery and secondary, but for us, it's merely a time factor, my husband's GF gets less time because we live together and are raising a son. If I chose to live alone, I wouldn't mind who my husband lived with...
It is just emotional on the wife's part? The way I look at things in our experience is that I'm not primary because my husband loves me more or is emotionally attached. I feel like he is pretty equally attached to both of us.
Howver, if my husband lived in a different city (and 18 months is a long time) unless I was actively planning to move in with him, I don't see what right I would have to tell him who to live with...
Does that make any sense?