Questions: Relationships

I still love my girlfriend and everything, but her sister is so sexy and I just want to do it one time. How can I convince her?

This has been going on for a long time but with the internet, white men are able to show videos of their wife cheating without being shamed. Cuckolding is becoming a lot more prevalent and statistics show that a lot of white women are cheating on their husbands with black men. Do you think that most white women do?

Now before you give me liberal/SJW/PC response of i have to get to know their personality first, we judge and form a preconception of a person/life/personality based on their looks on first meeting.

e. g. a girl sees a guy in a fancy suit and she already thinks he's successful guy and may already peg him for a relationship, until she gets to know him and find out her conception of him were wrong and he works an office job and loses interest because reality did not match up with fantasy.

e. g. Similarly a guy who sees a girl with lots of tattoos might already peg her for ONS and not relationship material. This isn't to say in both examples people can't change their initial wanting to be with you if they get to know you better.

So the girl:
And let say you meet her at a local pub, club, or hell just out getting coffee.