Second. I noted in my opening screed my BPD mate's starting a serious relationship within days after our breakup. Indeed, she tried to start another 18 months ago when we were going through a rocky time.
Feeling I know enough I could probably write a book on the topic, I'll admit that while I understand the psychology behind this behavior, it's still one of the most difficult parts for any SO to deal with because that behavior naturally causes us to question the validity of any love/affection in the relationship they had with us.
Prior to dating, a friend of mine asked my now exBPD why she always needed to be dating someone and she replied that she didn't know why she did it, but she felt she had to do it. While we were together, she'd often tell me that she had difficulties being alone; just in general. She didn't like being in the house alone - or single. And no different than many other people, mine was with a different guy just days after we split.
As Clearmind said, someone suffering with BPD typically feels an emptiness inside; literally like they are hollow with this void inside of them. Relationships appear to help temporarily distract them from feeling this because they can adopt an identity based on their partner and gain a false sense of purpose due to the relationship.
The common breakup is either:
1. The person with BPD becomes dysregulated, abandonment fears are triggered and they end the current relationship - either outright or via self-sabotage (either way, it's because they believe their partner will leave them so they act first).
2. The SO of someone with BPD recognizes the dysfunction within the relationship and they end it. (but often #1 happens because the pwBPD already predicted this moment well before the relationship started).
My own research into the topic has suggested that if someone with BPD is abandoned first, they appear less likely to instantly begin a new relationship and will often try to win the partner back for a period of time first. If
they do the abandoning, data suggests they are much more likely to form a new relationship in a very quick period (often having a new potential partner picked out before they actually end things with the former).
That seems incredibly cold to anyone with a healthier concept of love and there are other disorders where this same behavior is indeed cold, done by people with no capacity for empathy, who also used the person as a supply and nothing more. That's typically not the case with BPD.
If they are splitting their former partner to an evil person, then yes, it's possible some of their actions serve as a maladaptive coping mechanism and also a way to communicate pain by being hurtful or punishing towards that former partner.
But really, that relationship hopping behavior serves two purposes:
1. It prevents them from having to deal/cope with the emotions from whatever occurred in the previous relationship (they are hurting, they lost someone they did love - even if that form of love isn't the mature form an SO would expect) and
2. It provides a new source of attention/affection (because after a breakup, someone who constantly feels unlovable is certainly looking for someone to make them feel loveable - even if it's temporary).
If that replacement relationship ends or begins to have problems, depending on the pwBPD's current view of a former partner they may have reflected on what occurred and may contact that former partner in preparation to once again bounce out of their current relationship and into a new one (which would be back to a former partner).
Of course, this is an endless cycle because all of it is done to avoid dealing with the emotions that they need to be address rather than hide or run from. But that cannot happen without them being taught more effective methods to cope with those emotions and great effort on their part to take control of their reactions to those difficult emotions.
I hope that explanation helps you.
