Bright, Your h may have opted for the bus as transportation because everyone is either working or busy and it may have proven to be more convenient for him at that time. As for this being the last time he pulls away, I don't see that at all. If he were actually going to leave permanently and never return, there would have been papers filed by now. You are "assuming" again and that stinking thinking makes you sad and brings you down. Try to look at it another way...he's still alive and apparently is doing well. You've not had to deal w/much of his MLC madness and yes, no papers for a divorce as of yet. You are still on civil terms w/him and he does send you a post card from Mars every now and then.
Bring out your happy memories when you are feeling down and sad. Your love is still very evident and there is always a chance he may return at some point. He's still working on finding himself and you need to dig deeper for patience and live your life for you right now.
Don't let your h's decision to take a bus ruin your day. It's just transportation to the airport...nothing more.
Hang in there.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.