Guys how do you let a married woman know you're interested?

I have no problem with strangers. When a guy approaches me I mention within a few minutes of chatting that I am married and usually 1 of 2 things happens. 1. He excuses himself and apologizes 2. He says he doesn't care and asks if we can fool around anyways and I then turn him away

The problem is with friends and acquaintances people that I already know and who naturally already know I'm married. My husband will sometimes start teasing me that some guy has a crush on me and he's usually right. But I being totally daft would have never even noticed on my own. Since my husband doesn't meet all of my colleagues I need to have my own way of recognizing. Since I can't tell its led to some awkwardness and a few friendships ending badly. My question is to men have you ever fallen for a married woman? If so and you've decided to continue to keep company with her or even pursue her despite how have you done it? How can I tell? Some of the guys have been shy so even harder to read. I need to know so I don't lead someone on. And if I do find out a guy has romantic interest or if I suspect it what should I say? Is friendship impossible? Or can we be friends just not close friends?
Guys how do you let a married woman know you're interested?
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