I guess I have less worry about a guy stealing her away as much as undermining our relationship. I have a lot of faith in her. Less so in other men in general. Of course, I feel a lot less stress over the guy she has feelings for that is already poly. It's the other guy I have some concerns about. But that's really a drop in the bucket.
"The devil IS in the details. It is a lot more complicated than knowing she can love two people at the same time. The daily grind can be demanding, and because she is the hinge, a lot of responsibility would fall on her."
You have expressed my concern better than I have been able to. I worry about feeling less loved. I will get less of the pie. Her heart may have the same feelings for me, but she will be dividing her available time in smaller chunks. It's just math. Now I know I can find a secondary person as well, but I feel that keeping one woman happy is a big enough challenge that the thought of two makes me feel tired. I remember the days when I was younger and dated multiple women. It sounds exhausting to me now. There's a part of me that feels like, "Great, now I have the chance to disappoint TWO women!"
Anyway, I'm not sure how it will all work out, but I really appreciate your words. It's uncharted territory for me. So I thank you all for your wisdom. It still might not be my thing when it's all said and done, but I'm willing to try and see.