I had a problem with my boyfriend. I broke up with him by accident. Later, I apologized to him the next day. He didn't call me back or change his mood, but he didn't delete me. Why?

This means that he is really angry. Talking when people are impulsive and angry is the most hurtful. Maybe it's because you broke up that it's so sad. People may get angry if they think you don't respect her very much. This is probably a punishment for not replying to you and changing your mood. He didn't delete you to prove that you still have a chance. He is just waiting for you to admit your mistake.