Is it really so unstable?
No. It's actually just you. My wallet has been open 24/7. Just staking away. I never have issues if I restart wallet and need to sync blocks.
Everything seems to run perfect on my end. getting about 10% a month staking rewards.
Maybe your Computer Clock is off?
My wallet also crashed a couple of times in the past, but that was during the syncing process and not after that. And the worst part is that when I restarted the wallet, the sync started from a much earlier date. But I guess in my case the crash was caused by the incompatibility of some of the programs that were running at the same time in my laptop.