Is this romantic attraction or just pure flirting?

Well, it all starts out when I had a moment with this stranger (business professional/officer) who visited the company to review our products. We happened to see each other for the first time and we did have a moment, he was gazing and smiling into my eyes, while I looked intently into his eyes. The moment lasted for 20 seconds or more and this was in the midst of his other colleagues as well. I didn't anticipate that he would return,but more than four months have passed now and I encountered him again. I was instructed by my manager to set up something before the business meeting. I walked into the room and there he was, focused, reading through documents and preparing for the event. When I walked in, he looked up, was staring wide eyed at me, watching my every move. His gaze was intense and dreamy, no smiling like the last time. The second time I was called into the room, he could not take his eyes off me and even assisted me somewhat in the midst of the meeting. He should be focusing on the business matter at hand.... right? It seems like he remembered the moment......it was just a moment months ago. I thought he would have dismissed it by now as nothing more than casual flirtation, but this time his reactions were stronger than the last time. What is the meaning of all this? I have never spoken to him though. During the course of this event I happened to notice a gold ring on his finger...married. We know in our hearts that we can't do anything about our unspoken attraction to each other...in then end it would lead to heartbreak. I have never flirted or spoken to him and he seems to be an intense and serious person. Is it possible to be attracted to someone passionately in an instant? I know we both felt somewhat of a connection. What is it about me that caught his eye? Do his actions seem flirtatious ...?