Asking for your presents back
Some people are consumed by anger after breaking up. They feel used and they want compensation. This makes even the least greedy people ask for their gifts back: they want to offend their ex-partner without thinking about what it makes them look like.
Why it’s harmful: After you do something like this, you won’t respect yourself anymore. And your partner will have a story to tell about how greedy and cheap you are. The more people who know you will be able to discuss this moment of weakness. Leave the past in the past and make your partner remember you as a loving and caring person.