A lotta people presume their BPD lover is/was "addictive," but it's an erroneous assumption. The need for intense stimulation (either positive OR negative) is what keeps people returning to a high-intensity or high-conflict relationship, and feeling emotionally hooked.
Growing up with strife/struggle in our home of origin, sets us up for adrenaline addiction. Chaos and drama FEED that addiction (think fight or flight here), which helps us circumvent feelings of calm and serenity that put us in touch with inner emptiness or sadness.
This issue makes us wholly DEPENDENT on another to invigorate our emotions (light OR dark), and gives us the sense of 'aliveness' we crave, but can't manufacture for ourselves. In a sense, we’ve come to believe the other person is the KEEPER of our pleasure and pain!
It's a mistake to think of anyone as "addictive." The individual we assign this meaning to is merely the catalyst that forces us to FEEL emotions we've been dissociated from lifelong. The bottom line here, is when we’re disconnected from our own emotional repertoire, we feel dead, flat, empty and lifeless in our core, which activates a relentless search to find another to help us escape these difficult sensations~ even if only for a brief time (some call this “Love Addiction,” but no such condition actually exists).
Feeling work is healing work. When we are taught to experience our emotions in the body and NOT analyze them in the head by attaching meaning and reasons to them for endless hours at a time, we begin to develop emotionally. We are now connected to an entire repertoire of feeling states, as opposed to only a few. This works for healing Borderlines incidentally, because helping them outgrow their BPD traits is key to them becoming emotionally centered, whole and productive members of society.
The process of re-associating a client with long-buried feelings they had to surrender in childhood in order to surmount their pain, is what spawns emotional development, which is the precursor to MORAL development and its natural outgrowth, Empathy.
https://www.youtube.com/watch?v=3Kth3l_tSfk