The difference between "break up" object and "break up" relationship is the context of the sentence the words "break up" are used in. For example if you want to break up a cube(object) you are taking it apart.
if you are breaking up with your girlfriend (person/relationship) you are also taking the relationship apart.
Its all about HOW you use the words. Though there are other words you can use for objects like destroy, smash and obliterate which are a little more dramatic to use to describe the ending of a relationship between two people........I hope this make sense lol