What should I do?

It sounds like he thinks you may have been talking about him. Just find him one day and say something like, "Listen, we weren't talking about you the other day. We were just talking about something personal to her, and she didn't want anyone else to hear."

Be direct. Let him know that you have noticed a change in how he acts around you since he stumbled across the conversation, and let him know that he was not the topic of discussion and that she was asking about 'girl stuff'. He'll understand, as most guys don't want to get into that topic anyway.

Than make the first move by asking him to go for a bite to eat or something.

well he thinks you were talking about him that day. if you are interested then ask him out or you need to drop a hint or two that you are interested.

maybe send him a simple email saying goodnight when you now he is leaving for the day, or a goodmorning email. maybe just a little sticky note simply saying hello. sounds silly but you seem to have a thing going that is slow, feeling each other out so small is good.

He thinks you are gossiping about him. Approach him about the incident, and let him know that is not the case. I would also suggest to your other co-worker that she shouldn't pull you aside like that again. It's a good thing your boss didn't see that kind of behavior.

maybe he thinks you two were gossiping about him. I would explain to him that she was asking you some personal health questions when he came around the corner.

It sounds as if he thought you were talking aboout him. Let him know that you were discussing something else and suggest going out for a coffee to get to know him a little bit better.

she probably threw a wrench in your stuff. stop talking to girls about who you like at work; cause they could be liking that same person. he probably thought you guys were talking about him. ask him hey what's up you seem a little distant lately. he'll explain why and if not well float on float on. there's nothing you can do but leave him alone after that

Stay away from mixing your social life and your work life.

It's a bad idea to get into a relationship with a coworker, even if you are certain he is "THE ONE". If he is, get another job, then see where it goes. Good luck.

Normal reaction to what one might have thought that you were talking about him. Find him and explain it was personal and that is why you stopped talking and not that you were talking about him. Truthfully, I might have felt the same way. It's just a normal reaction.

My be he thought that you and the other woman were talking about him, ask him why he does not say bye to you anymore and then explain to him that you weren't talking about him ,but women issues