What stops the traveler from seeing down the road? And what does the traveler say he would like to do but can't?

sorry I could not travel both

When we remember that this poem is a metaphorical visualization of the human difficulty of making decisions in general, we see that Frost is dividing our choice-making ability into two kinds of information, on which is based the "consequences" problem, as the existentialists would say.  Yes, in real life we can "see down the road a bit," but where the road "bends," (that is, where the consequences of our...

sorry I could not travel both

When we remember that this poem is a metaphorical visualization of the human difficulty of making decisions in general, we see that Frost is dividing our choice-making ability into two kinds of information, on which is based the "consequences" problem, as the existentialists would say.  Yes, in real life we can "see down the road a bit," but where the road "bends," (that is, where the consequences of our actions can no longer be foreseen), we not only can't see further but also cannot construct in our mind what "might have been" had we made another choice.  So the speaker can't see past "where it bent in the undergrowth."  But the reason for the traveler's choice is made clear, after describing the amount of wear and the very recent fall of leaves on both paths,  with the line: "I took the one less traveled by."  This is a character revelation, in that the traveler is seen as an adventurer, a risk-taker, a nonconformist.  He also remarks "with a sigh" that despite his desire to come back another day and explore the other path, the probability of his doing so is slim:

Yet knowing how way leads on to way,/I doubted if I should ever come back.

So the traveler (1) can't see all the way down the paths, (2) can't avoid the feeling of regret that he must choose, and (3)is "sorry I could not travel both."