I keep this in mind too when cancelling plans or trips in order to do 'important' corporate work. The business will never remember you did a day from now; but your partner sure as hell will.
It took years, several jobs, and therapy before my eyes were open. Nobody cares, you are a human and have a life, if your employer does not understand that you need a new one.
I am lucky enough to have savings and a very supportive partner, and even so it is stressful. Certainly without either or both of those things I would likely still be sticking it out at the current job (especially with the various things that were offered when I handed in my notice). I sympathise with those that feel trapped.