It would appear Remilia attempted to manipulate fate so that either Meiling and Sakuya were to be married, or perhaps Remilia and Sakuya.
Either way she screwed up and nobody is very happy about it.
Marriage CertificateMatchmaker (theme)GivenAoshima(how to read)GivenDate of registration: (x month in nth season) E.g., 1st month in the 4th summerFull nameMisc.WifeWife to beScarletRemilia"Oh, I see... Wha?"Wife to be"Wha?"OccupationHow they first met"Miladyyy! Sakuya-san is in a really bad mood... I wonder why...?"Master of the Scarlet Devil Mansion, Ladie [sic]Witness (artist)Meiling"Well... It's because you and I have been married by some mistake..."PhotoFamilyFamilyHongGatekeeperHong Meiling