Originally Posted by Krazykitty
I feel that this would pre-emptively fill the gap that would appear if/when my husband is actually seeing, being friends with, or sleeping with this woman that he finds so incredibly beautiful.
First of all, looks only get you so far. I'm sure you are aware of this by now or you'd never be with the guy this long. Second, it does sound like the two of you have some things to address in your relationship that adding more people is not only not the answer, but would actually complicate things for the worse. Third, I wouldn't want to be the new person getting involved with you only to come to find out that I was there to "pre-emptively fill a gap".
HOw does she feel about him? Has he talked to her? Gotten to know her as a person? Is she even open to dating someone in a non-monogamous context? I realize these questions are not what you are asking, but it matters as to how much of your husband's attitude is dictated by fantasy versus reality.