Is Borderline Personality Disorder the reason why even though I'm in love I still have the desire to cheat?

I feel like whenever my girlfriend isn't around I will overblow her negative traits and feel the urge to sleep with another girl to justify her imperfect behaviour. However, she's actually perfect for me, loves me and has very few flaws. Still I feel a need to get back at the world, including her, for the things that have not gone right in my life. Will I feel better if I fight the feelings and let my negative energy out in another destructive way, or should I just cheat and get it over with to satisfy my urge and bring back a sense of calm and justification.