MMmmm.... well for mental breakdowns...
So far we only got 1, and its that if you betray Cecily you will get occasional nightmares that will give lona a big mood debuff(PTSD).
but what you want is currently a Trait thing only, by changing personality.
Lona does already grow submissive when captured and got a gameover in the Fishtopia cave, where she is totally okay and happy giving birth there many times because Deepones gives her life necessities, Sleep in the Cave in a Captured state and then click "i give up", i think you need negative stamina for it.
TLDR: We kinda have it, but not exactly, Wish that it gets added later! :thumbsup: