I'm assuming, btw, that you know he's single by now - men who are being friendly but aren't hitting on you/think you might be interested in them usually manage to shoe-horn in a mention of wife/partner at some stage early in the proceedings!
(I have much previous experience of this prior to being married 
)
I wouldn't really take my advice, though - many moons ago, I had a lovely, and also flirty friendship with a colleague. I thought I was on the way. Conversation about something blah blah blah "I mean, it's not like you are gay or anything!" (My reputation at university was for an exquisitely tuned gaydar and for being a consummate fag hag) "Err, yes, I am..."
Shocked silence then, "Oh, you really had me going then - haha hah"
"No, I really am,"
Not my finest moment . But I was his Best Woman the following year, and many, many years later, when it actually became legal for him to be in a civil partnership, again. And for a third time when they married
We are still excellent friends, and his husband (and mine) still think it's hilarious that I spent months thinking I was getting somewhere (bastards ). And he and I still flirt outrageously too
The moral of this story is that even if it doesn't pan out romantically, you still sound like you are having the basis for an excellent and enduring friendship. And in 35 years time, you could still be close friends. And/Or married to each other
This really is far too late to be up when I've not been drinking, which is clear from the drivel I'm posting . But I think now you have to make a further move and test the waters a bit more obviously! Good luck!