The traveler is sorry that he cannot travel both roads at once. He is also sorry that he cannot see the bend in the road. Moreover, he has to make choice which makes him sad. After all he is a poet and is thinking about the whole project in a poetic manner. He is stricken by the unexpected. By his limited ability to see.
He wants to explore all the possibilities and given his immediate choice, he is sad that he will never get to see the other part of the road. In some way, he is also mentioning a fork. He has to leave some hearts broken and mend some other hearts.
The first-person narrator. This traveler on the road normally feels sorry about the things that he cannot tell because he is not able to travel both roads. He feels sad because he feels that he has let other people down because he was unable to travel both roads.
The choice that he makes is always difficult as it can affect the lives of other people. This is the same with how we live our lives. All of the things that we do are all intertwined. There are some choices you will make that can affect the other people around you. There are even times when the choices you make will even affect those that you do not know.
A traveler on a road has a number of thoughts. As he walks, a thought occurs to him, which saddens him greatly. As a poet, he has a philosophical mind and feels sad, as he cannot explore both roads. One destination will always be concealed.
As the first person narrator, he feels sorry because of his limited vision, as he cannot see beyond the bend in the road. As for the narrator he feels sad, because the choice of which road to take falls on him. It is a difficult choice, and one, which will defiantly leave some hearts broken, but he has to make it.
He feels sorry that he cannot travel both roads. He feels sorry that he cannot see around the bend in the road. He feels sorry because he has to make a choice.