Answer:
Possible theme:
Saying goodbye or the passing of a friend/loved one.
Explanation
"a dream-like image of someone passing away, or saying a final goodbye."
"The narrative sets up this subtle tension between the timeless attraction of the lovely woods and the pressing obligations of present time."
The Theme you could say is the thought of sui-cide. The woods here can be taken as the sweet release of death. But then the man believes he must still go on for he still has a long time to go before he meets the woods once again.
"And miles to go before I sleep, And miles to go before I sleep."
