I wrote a very long post yesterday as a reply to all of yours. But it disappeared. Bummer, it was quite extensive with all the necessary quotes and such. I'll write a very quick summary here:
I don't want to do anything in secret. One of the things that really click for me is the honesty act. I want to be open about it. But doing it behind somebody's back does leave certain issues under the table that will come out in an open relationship. I mentioned the secret thingy out of frustration. I try to be open about what so many other people do in secret and I get to answer to all the crap. (the poor me attitude)
And no, I won't be making a choice purely on the feedback I get on an online forum. But it does help to get a new perspective on things. And that is very useful when you brain goes in emotional loops.
She does have fear of the unknown stranger. But she has others too. It's not the physical part she is worries about. It's the emotional part. She kind of likes exclusivity around that. Gives her the feeling someone is going completely for her. But the focus changes, sometime the unknown is the big issue, sometimes not having control. Or sometimes she doesn't like the idea of sharing the special thing that we have.
I'm a people person. I like deep relationships. I like the emotional connection. I like loving. I'm can love multiple people at once and I can love multiple partners at the same time. I like having sex with more than one person. I'm not great with words but when this whole poly thing was first hinted at me the first time I felt like I finally saw what was right in front of me the whole time. It just makes sense. I think it will be hard not to be able to live those things. It felt like coming home, just realizing that is actually how it works for me.
I looked in to the "itch" thing. And I don't think that is what's happening here. It doesn't matter that she might be mono and me poly. And I agree, that the rule about both seeing someone or it isn't fair is bonkers. But she can't cope with me having anything other than a "normal" friendly relationship with anybody. If it moves beyond that alarms go off and the special emotional forces move out in numbers. That brings a lot of tension and that is the reason for the current situation in my humble opinion.
If things don't work out they wont. But I like to try first. We had leaps of faith in the past. It was rocky from the start, but then it was the two of us against what ever was out there. Now it's something between us. We did grow just taking all these leaps and I will be the last who just ends it when the first (real) problem arises.
But it's a tough one. Between a rock and a hard place.
Also, the replies have been very useful. As I said, it breaks the loop I'm in and puts me back on the ground.