I have always worked in a male dominated work force, so I get to hear how guys think. One of my collegues once told me "if you're going to "cheat" make sure you cheat with someone who has more to lose in life if it all comes out than you do" pretty twisted advice, but makes sense :) I forget where I wasn't going with this and how it applies to your question ... lol :)
Whenever that has happened to me, I've been with a friend an we met a couple of ladies. There was no chance I could cheat without anyone knowing. If the right girl came along at the right time, I think I would give in. Then again, if she was that good, alarm bells would go off and the fear of falling for her, ruining my life, and losing the respect of my children might keep me from doing something I would regret. I've been torn between two lovers before and it was hell on earth. Nah... on second thought, I think I'd have to get out of that situation.