I think that this is more a career question than a financial question. Yes, you can afford to live on €90k a year. And if you find that you can't, then you should be able to move back to a full-time job.
It's a very big leap from two high pressure jobs to working 3-4 days a week.
Could you not switch to a different company on 5 days a week without the high pressure?
In the few cases I have seen, senior people who reduce to 3 days a week, often end up working on the other days as well.
If you are working as a secretary or shop assistant, you can work 2 1/2 days a week and that is that. But in senior roles, you can't usually just switch off at 5.30pm on Wed and say "See you on Monday at 9 am."
So there is a real risk that you will end up still in a high pressure job but just being paid half of what you were paid.
Is the pressure time pressure or some other pressure?
You might find that you need some pressure but not too much.
It's probably worth having a chat with your employer about how you feel.
Brendan