1. Deep emotional memory: The emotions invested in unrequited love are pure and profound, often accompanied by beautiful fantasies and unfinished expectations. These emotional memories leave a deep impression in the brain and are difficult to easily erase.
2. Habits and Dependence: Long term attention to the details of a crush's life has formed a habit or dependence, even if one realizes that the relationship may have no outcome, this habit is still difficult to change immediately.
3. Unfinished matters in the heart: Secret love is often accompanied by unspoken emotions and regrets. This feeling of "unfinished" will create a sustained driving force in the psyche, prompting people to constantly recall and linger, hoping to find opportunities to make up for or complete that unexpressed emotion.