When did you realize your (semi) major life decision had gone bad?

[neuroman]

Think back in your life upon major and semi-major decisions you've made, choices that heavily impacted your life for at least 3-4 months or more. Cities you've chosen to live in, colleges you chose to attend, jobs you've taken, etc. Something like "I bought a crappy car and regret it" isn't what I'd qualify as a major life choice, unless for example, you paid way too much for the car and the consequences of your purchase impacted your life in other ways.

Now think back to decisions of yours that resulted in bad outcomes. Did you anticipate or at least appreciate the risk of a bad outcome at the start, and to what extent? (Let's except romantic relationships for this point, obviously those ALWAYS have the possibility of ending badly.)

When did you realize or begin to realize that your decision was causing adverse consequences in your life, and you should do something else instead? (Leave cities, change jobs, etc.)

At what point did you decide to "cut bait" and acknowledge that despite any sunken costs, what you were doing was not the right thing for you? What did you do to fix the problem, if anything? Did your fix work?

I realize the questions I'm asking require much more introspection than the average OOT thread but I would love to hear your responses. There is a personal context here but I'll wait because I don't want to make this thread all about me.