He said to them: Although Moses permitted you to separate from your wives, due to the hardness of your heart, it was not that way from the beginning. (Mt 19:8)
λέγει αὐτοῖς ὅτι Μωϋσῆς πρὸς τὴν σκληροκαρδίαν ὑμῶν ἐπέτρεψεν ὑμῖν ἀπολῦσαι τὰς γυναῖκας ὑμῶν:, ἀπʼ ἀρχῆς δὲ οὐ γέγονεν οὕτως.
Ait illis: Moyses ad duritiam cordis vestri permisit vobis dimittere uxores vestras; ab initio autem non sic fuit.
In the Greek dictionary, the word “heart” appears as part of complex expressions: καρδιογνώστης kardiognōstēs – knower of the heart (Acts 1:24); ἀμετανόητη καρδία ametanoētē kardia – foolish heart (Romans 2:5). God knows our hearts and wants to give us a heart of flesh (לֵ֥ב בָּשָֽׂר leb basar) and take away a heart of stone (Ezekiel 36:26).
People tend to look for someone to blame when conflicts arise in relationships. The Gospel makes it clear that ultimately it is about a hard heart. Always, in such situations, someone has a hard heart that has closed itself to love, forgiveness, sacrifice.
