picture credits to Zack Ahern
People tend to say bad things to the people they care about. Its one of their way of taking care for the others. They don't know how to show it or how to express it, hence the inappropriate actions. Human's emotions are complicated. This is a mistake that anyone can make.
After all, human are imperfect.
If there is no fights and thorns in a relationship, then it is not one.
One thing for sure, people learn from mistakes.