Mutually Adapting to Each Other
A partner is a person as he is, he is not raw material to be lured into a relationship and then exposed to attempts to change him.
That has implications. Until getting involved, until the entering of commitment, it is for both the phase of discovering, if they mutually can accept each other without attempts to demand change. At the moment of entering commitment, this is the implicit acceptance of the other as he is at that moment and the conscious denouncing of attempts to change him.
But the other has also obligations. First of all is to reveal his true self sincerely and without limitations, restrictions and reservations. If one has to accept someone at a given moment as is, he has the right to know, whom he accepts.
This covers all that is the core personality of the other, values, attitudes, opinions, judgements, likes, dislikes, tastes, interests, needs, and all tendencies, that are hard-wired into the brain. It is either acceptance or a dealbreaker before getting involved.
There is one exception, and that is habits. Here both have to adapt to each other, until none has habits, that are irritating, disgusting, embarrassing, risky, destructive, wasting resources, in any way detrimental for the couple as a unit.
The process of adaptation means to give feedback concerning the perception of such habits in the form of constructive criticism. That means, the feedback is clearly limited to specific behaviors including suggestions, how to improve it and the willingness to give support in doing so. There has to be a mutual agreement, that discomfort or disagreement with specific behaviors is not a a rejection or devaluation of the person but limited to the behavior.