Expectations

Somebody probably rightly said once that expectations screwup everything. But how about in a romantic relationship? Is it possible not to have any expectations in a relationship at all. Do we have boundaries here too?
I know we need to understand each other in such relationship and behave accordingly. But is it too childish to feel we have right on the other person? Is too childish to be concerned(?) on partner's health? Is it too much to ask anything? Is it too much to feel having a right in partner's life?
Being childish?
Am I not understanding the difference between possessiveness and ?
Too incriminating to feel or express emotional dependence?
Is companionship not for a life time?