This is a very interesting post. I'm not sure what a waif is, although I hear you qualifying your thoughts in that we can't overgeneralize, all are individuals etc.
Personally, I feel there is virtually something spiritually missing when you deal with any Cluster B.
This is one of the obstacles for a lot of 'non's who embark on a r/s with BPD, whether unwittingly or knowing what is being gotten into, e.g. staying after abuse or discarding. I wonder about whether BPD can have an authentic spiritual life because part of the currency of relationships for most of us is some form of Golden rule. Every faith has a form of this. Yet a cluster B, or for that matter a full on psychotic who hears voices and detaches from reality (which is comorbid with about one-third of BPs according to Pubmed studies), couldn't live by this because his/her needs are so overwhelming, and narcissism which is present in all cluster B's leaves no room for genuine compassion or caring how another is doing/faring, even someone they claim to love. Loving someone requires decisions that are at times in conflict with one's own self interest, based solely on an ethical compass -- e.g. not to cheat, lie etc. B's needs are so overwhelming what's to stop them from doing any action destructive to the r/s (or themselves) if it provides temporary respite from the emotional pain? So golden rule is out the window. And faith requires constancy, while BP in particular lacks this trait.
Only exceptions being the more insightful B's who commit fully to healing and have the resources (time and money/health insurance) for competent, intensive therapy. Then again, it's chicken and egg because for someone to go through the hard work of unearthing and re-living, processing whatever past trauma(s) led to the disorganized personality, they must have some kind of faith in the healing process, which might reflect a belief in a higher power.
Isn't it odd that the badly put -upon non can end up experiencing feelings of e.g.anxiety / turmoil / depression / being out of control / unable to focus... .JUST like the deep -rooted, negative subconscious feelings the BPD has in spades and is ALWAYS fighting to suppress?
This idea actually came up in a counseling session. I wonder if people who act out, in whatever manner, are not setting out to harm another so much as they are trying to feel less alone, so they keep acting out until people close to them join them in the disorganized feeling? I've always been interested in pathology, curious what is the ultimate payoff for someone who knowingly mistreats another person. There's more to explore in reading about attachment theory.
It may be one reason a BP feels familiar to us, or like we've found our "other half"... .we all experience this aloneness and yearning for attachment. But this yearning will be forever frustrated with a cluster B who remains untreated. At any rate if viewed through this lens it's easier to depersonalize their behaviors, whether raging, ghosting etc. Has nothing to do with us. And we all need to carve out our own path toward union, which can be a blend of friends, family, work and hobbies in which we immerse ourselves etc.
Again, the honeymoon period is O.V.E.R and for many of us the realisation we are now dealing with a cold, calculating sociopath is often a starkly dispiriting one (devastating for many).
I can relate... .the stalking was all about his needs and very much to my detriment. Shows absence of the golden rule and empathy, at least for that individual. First I had to grieve the end of the relationship, but I couldn't stop there... .added to that has been on-going terror, all the while grieving for the depth of the waywardness in someone I had respected, and whose potential for healing I believed in. Very tough stuff.