I catch my sister having sex with her asshole boyfriend

I will never understand how my sister can be dating that asshole but that's the way it is and I have to respect it, now, if he hurts my sister or cheats on her I assure you that I will cut his balls off so I hope I don't have to do that... for now you will see how with a girl like my sister it would be an asshole to go with another girl because the girls in Spain are the ones who fuck the best.