In Robert Frost's "The Road Not Taken," what is the narrator's state of mind?

For one thing, there has long been some question as to exactly who the narrator of Robert Frost's "The Road Not Taken" is as Frost has created a mysterious reading experience in a rather short poem.  One more than one occasion, it is documented that Frost claimed that his poem was about a friend of his named Edward Thomas, who possessed a penchant for indecisiveness because of a strong habit of dwelling on the irrevocability of decisions.

If Thomas, indeed, is the model for the speaker, then the narrator's state of mind is yet his indecisiveness. In Stanza II, he demonstrates this propensity:

Then took the other, as just as fair,

And having perhaps thehbetter claim,

Because it was grassy and wanted wear;

Though as for that the passing there

Had worn them really about the same,

Even after years, the speaker is still dwelling on the possibility that the other road may have been as good a choice.  This compulsive lack of decision continues into the third stanza where the speaker reflects that both were equally appealing: 

And both that morning equally lay

In leaves no step had trodden black.

While the narrator as Edward Thomas rues that he could not make more than one choice-- "I shall be telling this with a sigh"--Frost seems to be satirizing his friend to the end as the speaker maintains his self-debate to the end.