if i got a gf i would never get attached and after having sex would basically give up on the relationship. still would be in it, but not be emotionally invested in it. if she cheated on me i would say okay and end it. theres nothing you can do anyway. beating up chad will probably get you arrested or knocked out, and fighting for a woman that doesn't give a fuck about you is beta. i don't plan on marriage, so why get attached in the first place? fuck her as much as you can and when the relationship runs its course be grateful you got it in.