The song doesn't just show regret from one side. The woman is also in the picture, represented in the character's reflection on you. That choice gives the story an interesting sense of uncertainty. Andes keeps the song's regret from becoming overly dramatic by having a character with plenty of opportunity to reflect on his decisions sing it. The image of the man alone at the bar, contemplating the road not taken, is at once specific and universal.
Andes had kept the opening line around for a while because of the attitude it showed about the character. "Old Man Bar" is a portrait of hindsight, funny in parts, bittersweet in others, and rooted in the uncomfortable realization that romanticizing one kind of life can mean overlooking another. This is a character study of choice and consequence and the versions of our lives that exist in our imaginations.