I think one of Immanuel Kant's categorical imperatives; “so act as to treat humanity, whether in your own person or in another, always as an end, and never as only a means” applies to your question. Because our needs and wants, and the ability or willingness of our partner to meet them, shift all the time, we need his rule, precept or principle to guide our actions or expectations at any given time, independent of a particular situation. Along with Aristotle and other philosophers, Kant saw “happiness” as one of the ends. His categorical imperative assumes that people are prudent, autonomous, rational beings with a free will. In other words, if what makes us happy harms others (e.g. stealing), or if we are in a dire situation (a heart attack), the imperative does not apply. This is of course a complex issue. In short I would say, outside general human decency and respect, we can “expect” our partner to meet our needs if it makes him or her happy to do so. This is why I always stress to communicate our core needs, expectations, and values clearly, and define what the shared purpose/end of the relationship is that makes us happy and fulfilled. This avoids making our partners to means of our ends and not theirs. I have been guilty more than once of doing that. I now realize that it makes no sense to be with someone who would become unhappy by meeting my needs and ends, or make me unhappy and unfulfilled by meeting hers.