There's no reason you can't find the new job before ditching the existing one.
In hindsight, I shouldn’t have taken the job in the first place, but I had just been laid off.
I knew they weren’t going to make me full time and as a contractor who was already being watched closely I couldn’t have multiple “doctors appointments”, take advantage of flex time, etc. I needed to focus on getting a job full time.
It was 2012, the economy was looking up and I figured I could get s job relatively quickly through my network of recruiters. I walked out noon on Monday and called a recruiter. I had a phone interview with a division of what was then a Fortune 10 company on Wednesday, in person Thursday morning and an offer Thursday evening making $10K more than the job I was laid off from three months earlier.
Yes that was partially dumb luck and not something I would try again.
The practicals of doing this will vary of course. There are many factors to keep in mind and a lot of them are personal/subjective.
It might not always be simple or easy but if you're in a bad and unfulfilling relationship then it's up to you to swallow hard and move on. Staying is lost opportunity.
A divorce has both higher emotional cost - especially if you have kids and are close to your in laws - and financial costs. If my job causes undo stress and hardship, I will leave at a moments notice. If my marriage is causing me stress and my spouse is willing to put in the effort to help us come to a better place, I’ll do what it takes to make things better. I’ll go to marriage counseling, but there is only so much you can do in an organization.
You might decide to live with this but again, if you started thinking about it to the point where you consider breakup then it's likely a serious enough issue and it doesn't get better.
This shouldn't stop you from trying to the point where by all definitions the relationship is dead. There's no rule for this other than a rule of thumb. But that one pretty much suggests at that point you are just delaying the inevitable. Unless all you actually need to fix it is time.
This is certainly the advice given if you're ruthlessly careerist, and it can be a good strategy if you're still looking for that dream role, but it can also backfire on you.
As someone who often needs to recruit I pay fairly close attention to the stability of an applicant's career. In general I don't like to see a lot of job-hopping unless it's in the early years of someone's career, because it can be hard to find a role you really like. Periods of contracting are another exception, although some evidence of stable employment for some period is also beneficial.
Recruiting is hugely important, but sucks a lot of time and effort from a team, and incurs significant costs, both direct and indirect. If you've been working for a decade and have never been in a job for more than 2 years that can be a pretty big turn-off.
You could of course argue that because I'd prefer to recruit people who will stay for more than 2 years, the roles I have available may not suit you.
Bottom line: there's a trade-off you're potentially making by behaving this way, which is fine, but it's important you understand that fact. Still, it's a good idea to start looking for a new job before you've started to hate the old one (bitter experience speaking right here): leave on a high because it'll probably set you up much better for the future.
I was working as an M&A analyst at an investment bank, and this job has an implied shelf-life. A typical program is two years, and some people stay on for a third year as an "Associate I". Your options for jobs after an investment banking analyst program are much narrower than I estimated when I left college to seek my fortune. Analysts will usually go one of three places: private equity (or venture capital depending on your background), corporate finance (M&A at a big company), or hedge fund. The sad truth that haunts me to this day is, I thought my duty was to quit when my time was up. An Associate I position was not available at my bank after my two years, so I decided to leave. I interviewed for a few positions before leaving (one of them serious), but I didn't receive any offers. I was burned out and really just want to get out of there. One of my coworkers asked me what I planned to do when I left. I said, "Whatever the hell I want." One other serious misestimation on my part: turns out I was not enthusiastic about fighting for a job in an industry that already had too many people fighting for not enough scraps.
I required a lot of time and self-reflection to not get some combination of angry, sad, and ashamed when recounting my time in finance. One thing that still upsets me today is, I was a naive 25 year old who didn't even understand the terms of my employment. I was not a contract employee; our agreement was employment-at-will, and I was under no obligation to leave. Yet, the HR department at my bank hardly even acknowledged that I was leaving. Someone told me to leave my keycard and Blackberry on my desk before I left. No exit interview or discussion of any kind. They really let me down because I was clueless. Could I have asked a lot of questions? Yes! And if you are in a similar situation, learn from my mistake. Ask a lot of questions, and find the right people you need to be asking. The thing you should understand about investment banking is, it tends to be a conservative environment with a strong hierarchy. Analysts are at the bottom of the hierarchy. The best analysts are those who efficiently do what they are told to do. I was very good at not complaining even when things sucked, and I was pretty good at the actual work too. But unfortunately, when I thought I was being told to leave. I followed that order too well, and I didn't complain.