There’s also a lot of overlap with anxiety disorders.
anxiety disorders as well as depressive/mood disorders, and impulse disorders. my best/closest gal friend struggles a lot with impulsivity in romantic relationships. not in the more extreme way the DSM describes, with binge eating, unsafe driving, promiscuity, that sort of thing where impulsivity is a way and danger of life, but for example, when shes flooded with abandonment anxiety, she will flip out, send her partner a cascade of texts, do self/relationship sabotaging things. shes a very jealous partner, snoops. she regrets it all later, but doesnt have the tools to stop herself and regulate. it looks a lot like what i experienced with my ex.
an insecure attachment style can look a lot like (and is often synonymous with) BPD traits as well.
However, when you compare normal relationship conflict versus BPD conflict, you have to draw the line.
i think it depends though, on where we draw it. a lot of the conflict here is common, if dysfunctional, every day stuff like:
-fighting over money
-fighting over the kids/parenting
-fighting about other family members
-fighting about friends
-fighting about/during holidays
-fighting about what to do/where to go
-fighting about time together/time apart
-not being on the same page about the future/timeline/commitment
-fighting over "vices"
-fighting about the sex
-fighting about division of chores/labor
-fighting about who is "giving more" in the relationship
-fighting about how each handles conflict
-significant differences in values (broad)
-boredom or stress
a key difference to me regarding BPD traits is that most relationships dont involve, say, threats of suicide, or the frequency/extremes of emotional dysregulation and high sensitivity. mental illness (severe or mild) by and large speaks to/effects how one copes with conflict, and/or life in general. most relationship conflict itself, is nearly universal.