Relationships are difficult, even under the best of circumstances. All the obvious categories can line up - good chemistry, compatibility, and good communication - and still it is not easy. Day to day living in a relationship requires an ability to stay present, be resilient, and be open. If you do not have a strong sense of Self, an inner confidence in who you are and what you have to offer, you will always sabotage the relationship.
A healthy ego is different than a fragile ego. A healthy ego is self-referring; it does not need another person to say or do anything in order to feel good. On the other hand, a fragile ego depends on others. Because the initial strength is not there, one becomes wounded easily, projecting that uneasiness to another; "If only she would have said it differently," or "If only she would agree to do the things I want to do," he tells himself over and over, never taking responsibility for hearing it the way he has heard it or the life he has created.
If you have an unhealthy, fragile ego you will often feel victimized and feel the relationship is "not equal". An unhealthy ego will change but only to gain points in the relationship, chips to barter. You will say things like, "I've accommodated you more than you have accommodated me." Using accommodation in this way is the opposite of love and score-keeping at its worst. Why "accommodate" if you are going to keep score?" To me, if what you do is not what you really want to do and is just a ploy to have a relationship, it will not be a relationship worth much.
When you have a healthy ego (sense of Self), you do what you do unconditionally. If YOU decide you want to change based on something your partner said, YOU do it for YOU and take full responsibility for the change. You do it because you know your life is better because of it. And the love gets deeper. You never bring it up as a bargaining chip because it is something you want to do anyway; and you are grateful for the change. And if it is something you don't want to do - don't do it! No one wants to hear either directly or in sub-text - "I did something I didn't want to do for you so you need to do something you don't want to do for me."
Be careful and vigilant if when you are taking with your partner the subject is abruptly changed and you are told you need to say it "differently". It is hard to catch this subtle switch and the next minute you find you are defending your position rather than talking about what your were talking about. Do not agree to a "walking on eggs" relationship and don't feel pressured and become something less in order to stay in the relationship. Fragile egos are tricky and if you are not intimately connected to your core and your peacefulness it is easy to get sucked into an unloving, draining, score-keeping relationship.