
Boundaries aren’t about your gf and her friend, but what you’ll do if they are broken. So the boundary would be if your girlfriend begins hugging and kissing her bestie, then you’ll break up with her. In this case, I think communication about what will make you feel uncomfortable is more appropriate. You can’t do anything about it, but if she cares she’ll appreciate your opinion on the friendship and change her own behavior. If not, then shucks.
As a religious person, possession is not at all what God wants for marriage. That is oppressive and controlling. You can argue that a woman must respect her husband but what you would really be suggesting is she must fear you. Fear comes from punishment and respect comes from a pure desire to honor someone. Check your intentions because there’s no fear in love and marriage is not meant to be oppressive.
Something like “I feel uncomfortable when you’re alone at your besties house after 10 pm.” Could result in either her not doing that, or shifting behavior to soothe your worries such as texting you updates or hanging out with other people there too. Either way that’s her decision, the only thing you can control is how you convey your emotions and how you react to her behavior.