The more I read this twaddle, the more I'm convinced the OP is getting off on online attention. Talk about making something out of nothing. He seems to think there is more going on than there is. Because its all in his head. Quite possibly the work colleague considers him a dodgy, somewhat creepy middle aged man (hes bound to be older than her), and possibly many of his younger female colleagues do too, but they are bound by workplace courtesy to be polite to him. And now hes getting even more attention from a bunch of women on the internet.
You're not my sister's mate, are you? He moons after women for months until they fall for him, then he's fine for a while then he starts pining after someone else
Alternatively, this type of man is usually to be found on POF or other internet dating sites, stringing women along by pretending to be single, constant messages, but never meeting up because they're absolutely terrified their long-suffering wife will leave him.
I bet the OP is actually terrified his wife will leave him, and this fantasy is all in his head.
ps OP the workplace is for working, not mooning about your colleagues. Just how good a performance can you be turning in if your head is full of stupid middle-aged man fantasies, instead of work issues?
Pure, pure fantasy, and rather creepy with it.