1. I don't get the interest in sex with different people; maybe because BTDT.
Wishful frustrated thinking on my part maybe.
2. I'm an introvert, too, so again why the idea of a closed, live-in situation was my personal ideal. I really liked having that 'other woman' in our life, it was often really fun. And there were times when I really appreciated her availability for things I either wanted to do and he didn't, or didn't want to do and he did - she could do it, and I could enjoy alone time.
I can grok that, we live on the same property under different roofs (I'm out in the back 40 too). I'm pretty sure another woman or even a man in our life would be a non-starter.
Plus, my libido was lower than his so he could get all the sex he wanted, and I could sleep alone - something else I really like to do from time to time. It may be that because we never did get to the level of living together with another woman, I had a rather romantic view of how it could all unfold, but at the time it seemed doable and a very inviting goal. And in my experience, most poly people are more of the multiple-partners each, so finding that perfect fit might have been extremely difficult. My partner today does not have any interest in any kind of poly, although I did try to persuade him it might be fun when we first got together.
This libido thing seems to be pretty common. I often feel like I'm in an old Neil Young song..."someone to cook the dinner, do the dishes and go away..."
And as I get older, the effort involved in developing another relationship seems too daunting, anyway, so we're all good here.
I have a friend my age who is struggling with teenage kids that my kids babysat. I feel for MH.
3. Yes, your grandkids are lucky to have such a great grandpa.
I'm the luckier one.