I just wanted to chime in with the WTH was wrong with Jen (and/or Sarah) conversation. NPD and BPD are thrown around a lot and both seem fitting to some degree, but Histrionic is an intriguing possibility in this case, to me.
For anyone unfamiliar with Histrionic Personality, here are the criteria. This article is comparing Histrionic to Borderline, but I've seen it compared with narcissism too.
HPD is one of 10 personality disorders recognized in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). HPD is one of the Cluster B disorders, which are characterized as dramatic, overly emotional, and/or erratic.
The DSM-5 defines histrionic personality disorder as a pattern of extreme emotionality and attention seeking behavior that begins by early adulthood and is obvious in different situations. In addition, you must have five or more of the following signs or symptoms to be diagnosed with HPD:
Discomfort in situations in which you're not the center of attention
Interaction with others that's often characterized by inappropriate sexually seductive or provocative behavior
Rapidly shifting and shallow expression of emotion
Consistently uses physical appearance to draw attention to self
Style of speech that is excessively impressionistic and lacking in detail
Shows self-dramatization, theatricality, and exaggerated expression of emotion
Is easily influenced by others or by circumstances
Considers relationships to be more intimate than they actually are
https://www.verywellmind.com/histronic-personality-disorder-425425
And, moo, I believe Sarah probably had her own disfunctional personality going on, maybe from cluster C (OCD or avoidant perhaps), but...
I'm not convinced there wasn't partner abuse in this relationship either. But unless someone who lived in that house is miraculously found alive, I wonder if we'll ever know for sure. I suppose there is plenty of time for more information to come out.
(OT I cannot thank the person who posted the Lundy Bancroft book enough. I can't locate your post right now, or remember the name, but thank you.)