Auden's take on the 'Road less travelled'

The Crossroads

The friends who met here and embraced are gone,
Each to his own mistake; one flashes on
To fame and ruin in a rowdy lie,
A village torpor holds the other one,
Some local wrong where it takes time to die:
The empty junction glitters in the sun..

So at all quays and crossroads: who can tell,
O places of decision and farewell,
to what dishonour all adventure leads,
What parting gift could give that friend protection,
So orientated, his salvation needs
The Bad Lands and the sinister direction?

All landscapes and all weathers freeze with fear,
But none have ever thought, the legends say,
The time allowed made it impossible;
For even the most pessimistic set
The limit of their errors at a year.
What friends could there be left then to betray,
What joy take longer to atone for? Yet
Who would dare complete without the extra day
The journey that should take no time at all?

WH Auden

What was bugging him that morning? And why so cryptic at the end?