Thank you for sharing your heart and this deep burden for your daughter. I join you in prayer for her freedom, protection, restoration and healing, and for your whole family.
You are right to see clearly what God says is true. Living together outside of marriage is not marriage. A lifelong covenant between one man and one woman is the place God has ordained for sexual union and for building a home, and anything outside of that cannot carry the blessing or security of marriage. What you are describing as greed, control, dishonesty, manipulation and financial exploitation is not love, and love does not isolate, divide, or exhaust. You are right to name that she is being used and not truly loved, and to refuse to call this young man her significant other or to put him before her faith, her God given family and the purposeful work God has given her.
I agree with you in declaring that your daughter belongs to the Lord. She is His, and He is able to protect her with all of His power. My prayer is that God will flood her mind with supernatural clarity and open her eyes to see this relationship for what it is and to see the spiritual battle around her and your family, the division, isolation, chaos and weariness that has come with it. Praying that she will recognize the difference between a wolf in sheep's clothing and a true shepherd, and that the Holy Spirit will speak to her mind, heart and spirit to walk away, to trust the Lord and to trust the family God gave her.
Scripture teaches that our relationship with God is first and primary, and when that relationship is right, other relationships begin to come into balance. Sin always separates us from God and harms our fellowship with Him, but God does not want a distant or merely ritual relationship with us. He wants a close, intimate and loving relationship where we know Him as our Father and know how deeply He loves us. That is what I am praying your daughter will return to and experience anew, a personal love for Jesus that is more compelling than any counterfeit affection, and that will restore her freedom, her self worth, her peace and her joy.
I am praying that the Lord will guide her to leave this harmful situation swiftly and without regret, and that He will provide for her, protect her, and restore what has been taken from her. I am praying for your family to be saturated with the presence of the Holy Spirit, with His peace, love, favor, protection and healing in every part of your lives, and that God will rebuild what has been broken and bring you back to that first love and close communion with Him where you find strength and wholeness together.
May the Lord guard your daughter and your home, give her courage to choose what is right, and bring complete restoration in His perfect love and care. In the name of Jesus, amen.