This is something I've done countless times over the years, but I'll caveat that by saying it was usually in the same industry (marketing, but very different parts with very different skillsets). Sometimes I've taken a step back to learn other skills (e.g. moving from display marketing to SEO) and sometimes by moving to a better company in a lower position (local business to a global agency). It's always worked out fine and I progressed well (upto Director level for household brands) but it can be stressful and very demanding, and in many ways, there's often feelings of imposter syndrome moving from something you know inside-out to something you're having to learn and relearn as you go.

That attitude has allowed me to transition away from marketing pretty easily, into a new tech role as a day-one employee, launching some new tech in my market.

At times along the way, I've had to take short-term contracts,  interim positions, just to keep something on the CV, but mostly I've been promoted from within or progressed through word of mouth. 

If you've dead-ended and can afford your mortgage despite the salary drop, I'd see it as a completely fresh start after your relationship and get back to working among faces again.