And, totally awesome that you and Mr Clean are enjoying each other

I think friends make the best lovers!!
Thank you - and I agree!
I wrote a bit about this on here somewhere before but Dude would say things like, "If we weren't dating, I wouldn't be friends with her." I think that is fine for a ONS or temporary NSA partner - but "dating" implies (to me) at least he potential for an ongoing relationship...and who wants an ongoing relationship with someone they wouldn't be friends with?!? (BUT, I understand that "dating" to some people means anyone they are seeing on an ongoing basis and, potentially, having sex with - to me, that would be "hooking up"...whatever.

)
So, I have been enjoying my sexual encounters with MrClean immensely! I don't want to let NRE cause problems in other areas of my life, so I have been aiming for a once-a-week or so engagement - which has worked out fine, as my schedule is really tight, but his is generally open (at least during the day on weekdays). TBH, although the sex part is new, it has an element of ORE (or ERE if you prefer) in that I don't have that anxiety that comes with being naked in front of someone the first time, we have been close enough often enough that it just feels really like "Finally, YES!" - I know he finds me attractive enough (even before the 50# weight loss) and for almost 2 decades we have a history of honest dialogue even about sensitive subjects, he knows most of my history, and what he doesn't know, to me, feels like "more of the same". (For instance, he doesn't recall that he knew that Rube and I had had sex back in the day...and I had temporarily forgotten that he had slept with SLeW - which doesn't feel weird to me because our social circles back in the day had a TON of overlap.)
So, last night he went on his first "First Date" in four years - and called me on the way there because he was nervous! I told him he had called almost exactly the wrong person - as I have been on, maybe, 3 "First Dates" in my LIFE (and 2 of them were 25 years ago!). Not my cup of tea - I prefer to hook-up with friends or pursue one-off encounters with people I meet "in the wild" (like at live concerts - harder in Covid-times). Meanwhile, he has been on, like, 1200 first dates (not really, obvi, but a LOT)! He (and strangely enough, Dude) is one of the more successful on-line dating males I have ever heard tell of - in terms of actual conversations and meetings. (Because he is an attractive, attentive, and [unlike Dude] a legitimately good person!)
So...on the poly (my) side...
When I first stopped in to propose my FWB offer a month-or-so ago (after a near-miss became a not-miss - because, as usual, I am a JACK-ASS!) he had mentioned adding a line about a poly-FWB blah-blah-blah that was not going to be a problem to his dating profiles. A week or two later he brought up that he had been thinking about it and he wasn't sure that adding that info might not just confuse the issue. Which I absolutely, totally, agree with! He is hooking up with a poly-chick-friend for sex - now. He is not looking specifically for a poly-partner (although he is open to the possibility, I think - but definately looking for a nesting partner). Adding the "poly" angle to a dating profile of someone who is looking for a likely-monogamous nesting partner seems to muddy the waters.
So, I went into this knowing that it would be a, likely, temporary, solution to our sex-less issue. What I am curious about, that the poly-boards might not be the best place to consult - is, when he asks me, which he will, when is the appropriate time is to become exclusive with a new person (and stop his relations with me )?