1. Emotional depth and involvement: The ex may have left a deep emotional imprint in the relationship, as both parties have experienced many beautiful or important moments together, resulting in a deep emotional involvement that is difficult to easily erase from memory.
2. Unfinished tasks or regrets: If there are unresolved emotional issues, unfulfilled promises, or regrets at the time of the breakup, these will become lingering concerns in the heart, prompting people to constantly recall their exes.
3. Psychological adaptation process: After ending a relationship, people need to go through a psychological adaptation period to readjust their emotional state. During this process, missing one's ex may be a normal psychological response until the individual can gradually accept and adapt to the new state of life.