“There’s a lonely man where I work. I know he’s unhappily married. I can see it in his eyes. You are going to say I should stay away from him because I have read you for years. What if I just want to have fun? The best sex I have ever had has been with married men. What’s to stop me? I know what I want and I know how to get it.” (Paraphrased)

Deciding the man is lonely from what you see in his eyes is absurd. I’d suggest you are reading your own loneliness in his eyes. The “best sex” to which you refer has clearly been short-lived and probably been of great cost to the men and their families.

Grow up. Leave married men alone. You might even find yourself in your own long-term, committed, authentic relationship if you decide to let alone men who already are!