The proverb, "There are always two sides to every coin." reflects to the fact that there is more than one way to look at everything? From this concept you can create one of the main presuppositions of life; behaviors are not good or bad, rather they're useful or un-useful in the moment. People sometimes seem to forget that last part.
The fact is that every behavior is useful in the right situation. With the right point of view you can see how something that is limiting in one way can be rewarding in another. A common example of this is the goal of putting no expectations on people in a relationship. It's very true that it would be nice if we could live free of expectations – however, it does not work that way.
Some sense of predictability creates feelings of understanding, safety and control over one's life. This includes relationships. We have certain criteria to determine friendship and, whether we want to admit it or not, expectations and criteria go hand-in-hand. The criteria we have to identify a friend are what we expect from them. Some common criteria include things like trust, honesty, compassion, etc.
If we add the awareness that criteria can be ordered in a priority sequence then some things we can allow ourselves to be flexible on and others we can not. If a person dislikes a certain type of music upon meeting them, then setting that as an expectation in the relationship will "pigeonhole" them. That expectation is an un-useful limitation on the friendship because it does not take into account that people's preferences can grow and change with time. Concepts more important than taste in music, such as trust, we can be less flexible about because if a friend does something to lose our trust in them (such as lie, steal, abandon, hurt, etc.), then the dynamics of the friendship can change drastically.
Even though a person can recognize a behavior may be useful in a different situation – in the immediate circumstances it may be un-useful, resulting in damage to the relationship. Admittedly it's not so black and white; some behaviors may hurt you, however you'll accept that it was not done with malice, rather it was unintentional. When a person repeats that behavior in spite of the fact it harms the relationship then there will reach a point where "I'm sorry" becomes insulting.
With all this in mind the questions we want to consider are; Can you allow your expectations of someone to be flexible on the minor issues while still asserting your values on the real important points ?; Can we accept that people change while still being careful that those changes do not go against our own highly valued criteria for friendship ?; Is it possible to accept someone for who they are today and expect that things may change tomorrow, while at the same time, know that it's okay to expect certain core components (such as trust, honesty, etc.) will remain something consistent?