At what point does leaving a job which pays good money and offers a load of benefits become justifiable, in terms of just being fucking sick of it?

I've been in a pretty typical corporate manager-ish type role now for about a year. The pay is fine, and I was lucky to find something with work-from-home flexibility during the pandemic.

At the same time, the company culture is deeply irritating, the work ranges from stressful to tedious to pointless, and I'm not enjoying life at all outside of building up savings. It's also likely they'll try and drag everyone back to the office once it's viable.

I've also apparently been underperforming (due to what I believe to be a genuine lack of guidance), and my annual pay review was essentially a paycut (a <1% rise with over 3% inflation). Overall, I admit that after I finished a big project in November that I've mentally checked out and have been neglecting things here and there. I just want out.

I have some modest savings and a promising interview lined up, as well as a partner whose willing to cover for me while I'm looking. At the same time, I'm wondering whether it's stupid of me to let go of a well-paid job in this context without another offer in hand?

I've arranged a meeting with my manager for next week to let him know I'm resigning, but could possibly swing this into something else if I am making a silly move. Do you lads think I'm making a mistake? Is there a smarter strategy here?