Marriage

"The matrimonial covenant, by which a man and a woman establish between themselves a partnership of the whole of life, is by its nature ordered toward the good of the spouses and the procreation and education of offspring; this covenant between baptised persons has been raised by Christ the Lord to the dignity of a Sacrament"

(Catechism of the Catholic Church 1601).

Love and bear fruit...

A sealing of authentic love between a man and a woman which reflects God's love for us.
God strengthens and sustains people as they enter into a loving bond with God and with each other.

They become one flesh...

Holy Scripture teaches us that man and woman were created for one another: "It is not good that the man should be alone..." The woman, "flesh of his flesh," i.e., his counterpart, his equal, his nearest in all things, is given to him by God as a "helpmate;" she thus represents God from whom comes our help. "Therefore a man leaves his father and his mother and cleaves to his wife, and they become one flesh." The Lord himself shows that this signifies an unbreakable union of their two lives by recalling what the plan of the Creator had been "in the beginning:" "So they are no longer two, but one flesh

( Catechism of the Catholic Church 1605).