Tobit, a devout and wealthy Israelite living among the captives deported to Nineveh from the Northern Kingdom of Israel...suffers severe reverses and is finally blinded. Because of his misfortunes he begs the Lord to let him die. But recalling the large sum he had formerly deposited in far-off Media, he sends his son Tobiah there to bring back the money. In Media, at this same time, a young woman, Sarah, also prays for death, because she has lost seven husbands, each killed in turn on his wedding night by the demon Asmodeus. God hears the prayers of Tobit and Sarah and sends the angel Raphael in human form to aid them both."
Long story short: Tobiah meets Sarah, they fall in love, and get married, and God uses the archangel Raphael as the messenger to help tie up loose ends and heal the difficulties of Tobit, Tobiah, and Sarah. The story highlights the power of prayer and God's response to prayer in love relationships. When a man and woman bring the Lord of the Universe into their relationship, it is unifying and powerful.
Prayer as a heart covenant, from the Catechism of the Catholic Church
"Where does prayer come from? Whether prayer is expressed in words or gestures, it is the whole man who prays. But in naming the source of prayer, Scripture speaks sometimes of the soul or the spirit, but most often of the heart (more than a thousand times). According to Scripture, it is the heart that prays. If our heart is far from God, the words of prayer are in vain.
The heart is the dwelling-place where I am, where I live; according to the Semitic or Biblical expression, the heart is the place "to which I withdraw." The heart is our hidden center, beyond the grasp of our reason and of others; only the Spirit of God can fathom the human heart and know it fully. The heart is the place of decision, deeper than our psychic drives. It is the place of truth, where we choose life or death. It is the place of encounter, because as image of God we live in relation: it is the place of covenant.
Christian prayer is a covenant relationship between God and man in Christ. It is the action of God and of man, springing forth from both the Holy Spirit and ourselves, wholly directed to the Father, in union with the human will of the Son of God made man."