I would say expectation are never wrong.
If you are a partner and if you not expecting anything from your partner then you are not loving each other.
Without expectation, I would say it is a commercial relationship.
I relationship partners are ready to smile and ready to cry but If you say "Expect nothing and you will never be disappointed." then nobody going to agree with that quote.
People will ready to face disappointment but they would expect something from their partner. ]
For instance, romantic dinner date or surprise shopping
or surprise birthday gifts or Be there in their Good and Bad time.
I hope it helps :)