A friend just left for a 70K
So to put that in perspective
I live my partner, and pay 600 for rent, warm for 120m2 The place was a dump when we moved in 10 years ago but we renovated it ourselves (a proper Grundsanierung) Shared expenses come to about 600 for my portion. We split expenses based on salary, so my partner contributes 400 as she earns less.
So from the 3k after tax, 1.2k is fixed expenses, 0.5k is fun, 1.3k is savings.
We just bought a plot of land north of Berlin with a few friends (again, cheaper! and more fun!) and am building a little off grid cabin with that spare time. Doing stuff like that with a group is just great. Its a break from this idea that it needs to be allll miiiiiiine! (evil villain voice), splits costs and splits workloads (you try mowing all that grass....)
Out of curiosity, 45k€/year in what industry and country (if you're willing to share)? And is this a salaried position or freelance?
If it's job in a company, have you tried asking whether you can go part-time? Family reasons or whatever... I think in some countries is now legally required that your boss offers you an option to reduce your hours or go part-time if it is possible in any way (I don't see why it shouldn't be for a "full stack web dev" ;-)). Can't hurt to try, certainly.
So I fear it is unlikely that you will find a part-time job that pays that much in most of Europe... But again, correct me if I'm wrong.