Answer:
borderline personality disorder
Step-by-step explanation:
Based on the information being provided it seems that this is describing a person that suffers from borderline personality disorder or BPD for short. This is a mental disorder which is characterized by unstable moods, behavior and relationships. Individual's with this disorder tent to have intense and unstable relationships because they fluctuate and characterize the relationship as either being all good or all bad in different moments. Such as described in the question.