It was shown that the love for his girlfriend was most of his "life".
He was on the island out of "modern life", yet continued to go on due to the love of his gal, the package, and of course wilson.
He was rescued & came back to modern life...Yet two of the main things that helped him survive were now dead - the relationship with his gal, and wilson.
That left one thing.
After delivering the package - what is the next step?
Early in the movie we see so many hints that "Time" is a big factor in his job - so much so that it intrudes into his personal life (like at the christmas dinner he n gal make a bet at what timing certain questions come into conversation).
Stuck on the island we often see his time markings on the rock, and his control.
When he gives up this control, gives up everything - symbolized by tossing the oar overboard after wilson died...only then is he saved...
So then he does not feel as "in" with his job anymore when he gets back - it's not important to him as it was (the other people at the party mention "tomorrow" this and that, but he mentions no words of time)....
What is his next step in life?
After delivering the package he is stuck at a crossroads - in reality with the truck, map, 4-way, etc. and also this is symbolic of crossroads in Life...
The only thing not dead is the package...And the gal was beautiful..
His life is now open to any choice - he can go in any direction he wants to...he now has his "wings"...but the hint is there that he may go the direction of the beautiful new gal that has just entered his life