I think a lot depends on your personality type. I wouldn't do it, but I like security, and I did have dependents for a lot of the time. I often wish I had been more adventurous over the years, though.
It sounds as though you have a safety net, though. If your partner is happy for you to make the leap, and it won't cause problems in your relationship, then why not? Before you leave, if you can put aside enough money to keep you going for a year or so, that would be ideal, as you can keep your independence, and maybe retrain for something that would make you happier. Do you know what you want to do?
We spend such a lot of time at work that it's important that we aren't miserable; but at the same time, you don't want to leave this role and find another that also makes you miserable but pays half the salary.