Hello, I’m having a hard time finding a direct definition and psychological explanation of what the conditions of obsessiveness and mimic type behavior post relationships. Relationships in this case can be Ex’s, Old Friends, and passed away family members. 
Some people keep items of others after they leave or pass away. Being unable to throw them away or destroy them. Sometimes these mementos are damaged or destroyed, Likely causing a person to become highly upset and angry. 
Beyond items, things such as food and smells are highly sought after and liked by the one with these behaviors, such as having a partner who likes Pina Colada, and now the person mimics that like and continues to drink it long after the relationship. 
The most extreme of this behavior has been a person mimicked their ex partners limp months after they separated and they did not have contact since.

Does anyone know what this behavior is called or why it forms?