Some people and even ourselves do make the mistake to repeatedly remind others of their mistake when they apologize. You can fix your break up and forgive graciously when your boyfriend apologize.
This is one of the mistakes we all make not only by lovers but also parents and teachers. It's a habit but it can be corrected. This may be your relationship breaker that causes your break up.
We all have our fair share of promises broken by someone who means a lot by us. When you were hurt by men before where you were constantly let down, you tend to pull away very quickly and easily when someone new makes the similar situation and you quickly come to a conclusion based on your past experience.
Did your boyfriend called off a date, apologize but what you did repeat to him where he made the mistake and it really lets you down and that it upsets you. It is good to open up to each other about your feelings and emotions such as telling your boyfriend what makes you upset and how you felt when he did something you don't like. However, the mistake is to keep repeating and telling how upset you were. Another way to repeat to him what he had done wrong is the indirect way that many of us made such as adding a hint of sarcasm to remind him.
It could be the way where you keep hitting on your ex and never let things go tat ruined your relationship. If you are serious and want to fix your relationship, then you should really forgive and not stay with a grudge for too long if he has already apologize. If it is just the first time and on very rare occasion, listen to his side of the story, and forgive if he is willing to make up for it.