You're right Red Pepper. My bad. I forgot about F's husband as well.
I agree the primary relationships are the first priority. I do think he needs to know if there's even a possibility of a relationship though. If not, he can continue working on the relationship with his wife and try to get past his feelings for F.
I for one would not be able to continue on the way he is currently. Could be because of my own similar experience of longing for so long.
"Thou art to me a delicious torment." - Ralph Waldo Emerson