He's the right age for QLC or quarter life crisis. More common than you think with guys hitting the ground running right out of college into a family and career; not deeply emotionally prepared for the forever part. Rapid rise to the top at work and suddenly peaking out leaves the rock stars looking around and asking "is that all there is?"
Used to only happen to 50 year old guys who had to work their way up over time. Remember blonde secretaries and red sports car movies?
You sound good with most of this. The runaways often want to slip through the back door into their old life without having to discuss their "lapse". They fear hearing about it every time they turn around. It keeps weak ones from coming back. Have you two talked about how to discuss? Boundaries? Rules? What's not fair, or plain hurtful? He may be more sensitive to some things than you think, even when he is trying to own up and face others.
