Mila, Dudess... I think things may have fizzeled between my WH and his OW. Probably because the affair was exposed. And because with our first child on the way, he needs to get a job and start focussing on life here. Unless their affair turns 'sour' (for eg. shameful in the eyes of common friends or family) I think the unrequitedness could be a real drag on their letting go...
I hope for everyone's sake, that the affair has fizzled. Exposure does seem to help in many cases.
Evidently, the unrequited "love" can go on indefinitely because it is never tested against reality. I could have told my H last fall that I was moving out and he would have to come back to take care of the house and dog. I didn't tell him, primarily because it was best for me, but I also wanted to give him time to let the thing play out. I think it turned out the same way it always did. But hey, maybe he just needs to hang in there a couple more decades . . .