That sounds about right BlackUnicorn. My wife expressed interest in her (on multiple occasions) to me, but never to our friend. Our friend has expressed interest in each of us separately, and has been rather open with her feelings. While I think our friend and myself would be open to the idea of a triad, or some other formation, I don't think my wife would be. Obviously I can't know for certain with out asking her.
From what I've gathered she seems to like our friend, but definitely not enough to take an action, she is more of a sub. That and she has some severe trust issues from past relationships, because of which I'm quite certain she wouldn't want to share me. The only way I see it working would be if my wife and our friend were to start a relationship first. If that happened then she might open her mind to the possibility. I feel deeply that if I broached the topic to her she would feel hurt and offended again, I accuse me of wanting to cheat on her. All rational thought would go right out the window. The most important thing to me is that I don't ruin my marriage, I'm not sure if I could handle that.
Perhaps if I give it time I can find a more natural way, less abrupt way to mention my feelings to her again. I'm sure it is a lot for anyone to hear.