I find this very hard to believe....it sounds like a badly written story....first off if ur so concerned they why dont u just stay up and see what happens?! Its really not that hard to figure out. If u come out and hes doing that then there........
you really need to catch him, so try finding a way to stay awake and keep your ears open, and when you do, you can say thank you and bye bye I'm off to my new lover.
Good Luck
This story is very very very hard to believe.
You have not actually caught him in the act of sex with this younger man? Maybe he is no bi sexual.
Can you tell me when he had his surgery? After having open heart surgery you usually have to wait awhile to have sex. It can be weeks or months depending on the situation.