Things look flat to me, richness in life abated and replaced by repetition of married adult life. My wife is extraordinary, so it is not an issue of person - it is an issue of internal struggle with satisfaction of the outcomes of the choices I have made to orient my married adult life. Before the married adult life, I had the single life and seemingly endless options, and choices could be made, changed, and remade within days. Now, this time will elapse in years and with the overhang of others factoring into the process, notably my wife and dog.
The rub is that I am extremely happy - I would not change this life for all the options in the world. Still, the world is flatter, and I am at a loss for why exactly this perspective change. I am reminded again of that influential book "Seasons of a Man's Life" that I read during business school, which articulates this feeling as a grappling with the phases of adult development. Even with self-awareness of a life's journey, such feelings cannot be avoided.