Opinions please.

I am 31F and married. Theres this guy at work, he always gives me a hug when I get there and when I leave. He is in a serious relationship, lives with her and her kids. We flirt a lot, I talk to him about my personal problems, he always listens. He never talks about his relationship, even though I know they are having a rough patch.

Today he walked by me and winked at me and make a kissing face, it was in front of many people.

My question is how do you know a guy is willing to have an affair or just flirting? Is this some kind of game to him? I guess it is fun, but sometimes I just want some dirty love affair sex in the work place ya know?? I dont like not knowing his true feelings towards me. This has been going on for about 1 1/2 years.