Is This Person Still Dating Someone?

I was best friends with this guy. We were very close and in love, but we just never told each other. It's been more than three to four years now, and i'm still in love with him. I don't know what to do. Sometimes the reason we get so caught up on some one is because we are so consumed by the thought of what if. And like a summer fling, or someone whom you knew for a brief period of time,. But maybe that period of time was very intense. You never really got to the point of making things official.