It is very important for us to be careful of reading too much into a poem, especially regarding the life of its author. Let us remember that the poet often creates a different persona to narrate the poem, that can often be incredibly different from the poet themselves.
The central repetition in this extremely poignant poem comes in the last stanza, where the first line is repeated again in the last three lines:
Two roads diverged in a wood, and I --
I took the one less travelled by,
And that has made all the difference.
Rather than concluding that this repetition indicates Frost's own awareness of how his life has turned out, I think we need to focus on the symbolic meaning of this poem and how its message applies to us all. All of us have had to make choices in our life that have led us to where we are now. The poem focuses on the way that we are often haunted by the idea of where we would be know and what our present would look like if we had made a different decision in the past. This is why the speaker in the last stanza says this with a "sigh." The repetition serves only to emphasise the haunting nature of the decisions we make and how impossible it is to go back and metaphorically take the other path, yet how easy it is for us to obsess over different outcomes and different lives we may have had. Therefore I don't think the repetition is indicative necessarily of Frost's own difficult life. It rather highlights the way that we all, no matter how happy our present lives are, wonder what could have happened had we made different decisions in our past.