Couldn't agree more with the inappropriateness... and I have been married to an older man. Wisdom comes with experience.
I have to point out, though, that most men wouldn't f*ck a woman 20 years older, but they wouldn't mind doing it with someone 20 years younger... utter hypocrisy.
To the original poster - you are nothing more than an ego boost to a man who is too old for you. He isn't going to leave his wife - men rarely leave for another lover. Tell this man to go pick on someone his own age.