Thank you all for your advice, replies, encouragement. I think mostly I am just afraid of someone getting hurt, but I suppose that is a risk you take with any relationship. I do believe that, in the beginning, they did have some expectations that this was going to be a fairly equal triad, which was obviously a bit naive. And, I suspect that since time has passed and some of the honeymood phase has passed, there are certain feelings about being left behind (on her part) that are coming up.
I have honestly been trying to live in the moment with this as much as possible, but when she expressed some concern that she wasn't bonding as quickly with me, I started to worry.
Redpepper, I love how you say that somedays you love the leaves more than you love your partners. I feel the same way sometimes.
Thank you all again! xoxo