What do you suggest if my fiancee has borderline personality disorder, will this ever see us happy. also how do i deal with her?

Seek psychotherapy.: Individuals with Borderline personality disorder benefit from a a type of psycho-therapeutic treatment called Dialectical Behavior Therapy in which they learn how manage their emotions and behaviors by learning more appropriate skills to cope better with their life. Significant others/family members of this individuals will benefit from family therapy to learn how to deal with this disorder.