Couples can stay in a Zostel.
Zostels welcome couples and also offer suitable rooms for couples.
While Zostel mainly caters to solo travelers and even small groups they don't discriminate against couples and also encourage couples to book private rooms for comfort and privacy.
Even unmarried couples can check into a Zostel and stay together.
Zostel does not indulge in your personal lives.
Even in hotel rooms unmarried couples can stay in a single room together as there's no law that prevents unmarried couples from staying together in hotels or Zostels.