Right now, I feel like I'm a 6, or very close to. I kinda tried mono, but had to turn that relationship into poly. While I don't think I would have said "okay, bye" if my husband hadn't been understanding and willing to give it a try, I think the relationship would probably have crumbled and we would be unhappy, separated or I would be cheating. Or several of these combined.
I don't think I could be happy in a mono relationship. I would feel like I'm not allowed to develop feelings for other people, and it would feel unfair as I have no control over such things.
And I certainly don't believe myself capable of loving only one person and not falling in love for another one. Even when I only loved Rag I knew it was temporary, because I hadn't met the next "right one" yet.