Divorce or broken relationships!
Personally I have against all odds survived, however I do know of few guys, where they have broken up, or / and had relations on the rocks! Hanging by their teeth over the cliff!
The instructor who did say this, gave up flying mainly because of this, to save his marriage with 3 children!
Commuting has been hard for many, myself inclusive, and know of many where commuting, long distance, not being there has been an important part.
Maybe before, when the money was good, money could keep the wife.girlfriend happy, however these days - there is no money, no reward, at least not now - maybe one day! Things it becomes hard when like this!