I make the assumption that we are rarely fully ourselves when facing others. We act, we react according to what the others say, do, or according to what we imagine they think, will think or will say. By projecting ourselves onto the others, by being according to how they are, we are not really ourselves. We are defined by the others, we define ourselves (at the beginning rarely consciously) through the others. In what follows, changing means becoming oneself.
Then, is there a more beautiful mark of respect -and love- for a partner than to be willing to change for the good of the relationship and the benefit of the partner? And to really begin to change! Changing is not changing to be someone I am not and I can not be. It is not changing my character. It is not changing to force me to be a nice person. As Jacque Salomé puts it, "Changing doesn't mean becoming someone else, it is becoming oneself, and accepting it".
Changing, to be oneself, is first of all a personal process, even though in some cases it is triggered by an event or a third person. But changing - to be oneself -, when it is done in the framework of a loving relationship, is in my opinion, the sign of a great respect for both the relationship itself, and the partner. Simply because changing, to meet oneself, is more difficult than breaking up, and way more difficult than making the other guilty of different problems.
Changing to be oneself means accepting one's mistakes. And by this, it leads to stopping exercising some pressure on the partner, even simple words, statements or questions can exert some pressure on the partner. And on the long term it can be destructive for both the partner and oneself. Changing allows to break this vicious circle.
The terror for someone who is changing is to face others' denial: the partner, the family, the friends, have trapped the changing one into how they have always known him/her, and this is a serious break to the change. Also some could say "you change because you are the one who have a problem, you are the one who causes troubles". This all makes the change even more difficult. And that makes the change an even stronger mark of respect, because changing (in order to be and to find oneself), even if it is a personal adventure, is almost always for the good of someone else. It can be to improve a relationship, a neighborhood, a working environment: a boss who is unreasonably strict with his employees and was seeing them leaving one by one decides to change, and the change can only be initiated by understanding why he is strict, not at all by forcing himself not to be strict.
A great help to the changing person, on the contrary, is to accompany him/her and to believe in his/her change. Then the change is fueled, encouraged and it can be done for the harmony of the couple, the office, the family. In case of a relationship, it leads to a long lasting and flourishing relationship: because each one has been respected: me in my change, and you through my change.