i know it's childish and stupid, take this as a creative challenge.

how can i ensure my companion and i will never separate? we trust each other, of course, but i want to make sure that we'll be able to part if and only if we both agree, otherwise one could ruin the other's life for good, ensuring he/she never unilaterally quit.

i thought about this: we put all our savings in a shared bank account and each one of us keeps only half the password. if you don't want to loose all your money you'd better agree with me to empty it before leaving!

the downside of this is that if one quits we get equally damaged. can you think of a better mechanism?

i fear there's not since if the penalties are equal we can always get equally damaged, else it's unfair.