This. I actually don't get unflappable vibes from Wilson, rather a longtime sufferer of the slow, insidious form of depression.
When I take a meta view, I feel the writers were groping around the first two years to get a sense of the character. There were also some marvelous subtext acted out by RSL and HL to round out their characters. However, looking at the series as a whole, it's hard not to take into account Wilson's underlying emotions. I think it's fair to believe we first meet Wilson in a better state of mind. Maybe his breakup with Julie eroded his confidence. After all, it was his third marriage as well, which had to take an emotional toll.

he fills up his life, with the triple duties of husband, doctor, and department head, adds on top of it needy lovers and a six foot two cripple with an ability to get into trouble, so that he doesn't have to face the problems or just the desires within him.
He's the poster boy for codependency.

...thus forcing him to face his own needs - first the superficial one to take a few days off and have fun with House...
I thought it was very endearing of Wilson to insist House come along. It was the first sign in the finale arc showing how much House meant to him.

...then the deeper ones, such as the need to be cared for, to be the center of House's attention and love.
This was such an amazing turn of events. I loved it and am still overwhelmed.

eta: Oops! forgot to add:
I just wish they hadn't thrown all logic and most chances of a new begin elsewhere overboard.
Logic notwithstanding, I see the ending as the start of a new chapter.