Because they forgot to pray together to the Holy Spirit and ask for help day in and day out..
A great prayer for husband and wife every morning:
We thank you, our Heavenly Father, through Jesus Christ, Your dear Son, that you have kept us this night from harm and danger and pray that you would keep us this day also from sin and every evil that all our doings and lives may please You. For into Your hands we commend ourselves, our bodies and souls and all things. Let your holy angel be with us that the evil foe may have no power over us. Amen.
(Luther’s morning prayer)