When Sophie was a teenager, she and her friends had a "sisters before misters" pact, meaning they'd never date each other's exes and they'd never let a guy come between their friendship.
"Sisters before misters. Girlfriends should come before boyfriends."
2010 — Marsha Warner, Greek: Best Frenemies, Harlequin Teen (2010), →ISBN, page 120:
"First of all, this competition is about Rebecca, not us, and though her being crowned sweetheart would be good for the house, we put our sisters before misters. Remember?"
2011 — Vikki SanSickle, Love Is a Four-Letter Word, Scholastic (2011), →ISBN, page 221:
"Are you sure? Because if you want me to, I can go with you. Sisters before misters and all that."