Obviously I cannot speak for everyone who lives with this disorder , but from my personal experience and others I have met it seems we all share a similar trait. Honesty. 
I was diagnosed 6 years ago (I am 23 currently) in addition to a couple of other mental illnesses , and really over the years of countless symptoms the one worst thing I have ever felt was finding out my girlfriend was texting a number of other men , flirting non stop and ultimately cheating.

BPD makes you so emotionally turbulent anyways
the separation anxiety
the fear to love , or more accurate to lose it.
I constantly had jealous episodes over the years with her , she would convince me that it's all in my head. i would self harm out of pure anger and guilt just for putting her through these episodes.
it got to the point of many suicide attempts and countless nights at the mental ward.

Please. I can't stress this enough
if you wanna f around that's fine no judgment .. your life.
But don't put us through this. Please.
I have had friends who commited suicide because of this and I myself have tried many times.

If hell exists , it's in the heart of the dishonest