Thank you for bringing your question to Just Answer!
Men are able to separate their sexual desires from their emotions much easier than women can. It is possible that he desired you physically, but since he already had a girl friend, thought he would just try to have sex with you, but not get involved.
The reason he avoids you now may mean that he feels guilty for almost cheating on his girlfriend, or it could mean that he's worried you will file a workplace complaint against him for sexual harassment since he attempted to have physical interaction with you in the office.
I'm sorry he isn't mature enough to handle this situation in a way that would be more comfortable for you, but it makes it clear that you really did dodge a bullet on this one!
He asked me 3 interesting questions when I made my foolish proposition after I knew that I would not do something in the office. What if he wants to interact physically more than once and I replied No only once you and he said something and I said Cant you stop yourself from being with me? He asked me do I plan on marrying again? And I said After what I have been through - NO! He also asked me something else but I cannot remember it now. By the way I pulled out of him that his young lady was overseas for a few months and when I said to him why didnt you say that you have a girlfriend he said that because it is a gray area, she is not his girlfriend but they will see what happens upon her return to the states (he mentioned about seeing someone, a friend he called her for 1+ yrs before to me). I dismissed her because he said clearly before that he was not married, had no girlfriend and no children. I am perplexed some because why has he not committed to her in his mind while it is more than likely that she would swear he is her boyfriend if someone asked her. What gives?
If I could answer the question of why do men want physical intimacy with one woman while they have another woman, I would be very, very rich.
He may actually have committed to her, but denied it when he thought he could have physical gratification with you. Men have denied being married, etc. many times when the possibility of physical contact is offered by someone else. My feeling is that he lied to you because he thought if he admitted to a girlfriend, you might not want to have physical interactions with him.