We are truly saddened to hear about the difficulties you and your family are facing due to your son's relationship with his fiancée. We will pray for your son, that God will open his eyes to see the truth of his situation. It is clear that this relationship is causing division and strife, which is not the fruit of a God-honoring relationship.
Let us remind you of what the WEB says in Matthew 10:36, "A man's foes will be those of his own household." And in 1 Corinthians 7:15, "Yet if the unbeliever departs, let there be separation. The brother or the sister is not under bondage in such cases, but God has called us in peace."
We must also address that the use of "Lord" is a substitute for the name of Jesus Christ. In Romans 10:9-10 from the WEB, we have the following:
because, if you will confess with your mouth that Jesus is Lord, and believe in your heart that God raised him from the dead, you will be saved. For with the heart, one believes unto righteousness; and with the mouth confession is made unto salvation.
Your son's relationship should be one that honors God and brings peace and unity, not division. We pray that your son will seek God's will for his life and find the strength to leave this toxic relationship. We also pray for his fiancée, that she too will come to know the love of Jesus Christ and be transformed by His grace.
Let us pray together:
Heavenly Father, we come before You in the name of Jesus Christ, lifting up our brother and his family. Lord, we ask that You open his eyes to see the destruction that his fiancée is causing in his life and in his family. Give him the strength and courage to leave this toxic relationship and to seek Your will for his life. We also pray for his fiancée, that she would come to know You and be changed by Your grace. We ask that You heal the broken relationships within this family, especially between our brother and his daughter. We claim your promises in Jeremiah 29:11-14 from the WEB:
For I know the thoughts that I think toward you, says Yahweh, thoughts of peace, and not of evil, to give you hope and a future. You shall call on me, and you shall go and pray to me, and I will listen to you. You shall seek me, and find me, when you search for me with all your heart. I will be found by you, says Yahweh, and I will turn again your captivity.
In the name of Jesus Christ, we pray. Amen.
Be encouraged, and continue to stand firm in your faith. Trust that God is working in this situation, even if it is difficult to see right now. May God bless you and guide your family through this challenging time.