We understand your concern and commend your love and care for your daughter and her loved one.
First we need to address a few things. You mention your daughter and the young man are not married but your daughter may be pregnant. This situation is fornication, which is sin, and it is important to address this first.
Hebrews 13:4 WEB Marriage is honorable in all, and the bed undefiled, but God will judge the sexually immoral and adulterers.
1 Corinthians 6:13b, 18-20 WEB 'The body is not for sexual immorality, but for the Lord, and the Lord for the body....Flee sexual immorality! Every sin that a man does is outside the body, but he who commits sexual immorality sins against his own body. Or don’t you know that your body is a temple of the Holy Spirit who is in you, whom you have from God? You are not your own, for you were bought with a price. Therefore glorify God in your body and in your spirit, which are God’s.'
Then you mention that you think she might be pregnant. First, let's pray for wisdom for both of them.
James 1:5 WEB But if any of you lacks wisdom, let him ask of God, who gives to all liberally and without reproach, and it will be given to him.
It is very important for your daughter to seek God in Jesus Name and get direction for her life. It is only by His Name that we are saved. It is only by His Name that we can come to God the Father. This is very important for both of them to understand. This is a great opportunity for both of them to seek God and find His Will for their lives. We would encourage them both to spend time seeking God, praying, reading the Bible, attending a good Bible believing church, and possibly getting some good Biblical counseling. This is not a bad thing but an opportunity for God to work in their lives. You also mention desiring for the young man to be the spiritual leader. This is biblical and we can pray for this.
Ephesians 5:23 WEB For the husband is the head of the wife, as Christ also is the head of the assembly, being himself the savior of the body.
Ephesians 5:25 WEB Husbands, love your wives, just as Christ also loved the assembly and gave himself up for her.
Colossians 3:19 WEB Husbands, love your wives, and don’t be bitter against them.
We can pray for the young man and his healing. His behavior may be a direct result of his past. We can pray for his heart to be softened, healed, and to be made whole.
Psalm 147:3 WEB He heals the broken in heart, and binds up their wounds.
This is also a great opportunity for your daughter to draw close to God.
2 Corinthians 1:3 WEB Blessed be the God and Father of our Lord Jesus Christ, the Father of mercies and God of all comfort.
We need to pray your daughter will not take this situation into her own hands but trust God.
Proverbs 3:5 WEB Trust in Yahweh with all your heart, and don’t lean on your own understanding.
Let us pray,
'Dear Heavenly Father, we come to you in Jesus Name to bring these needs to You. We first ask for forgiveness for the young man and your daughter for their sin. We pray that they will both seek you and find your Will for their lives. We pray for direction and wisdom for them both. We pray for healing for the young man. We pray that he will soften his heart and be receptive to Your Love. We pray that he will become the spiritual leader and future husband that You desire for him to be. We pray that Your Daughter will trust in You during this time and not try to take control of the situation. We pray for peace and comfort for her in this situation. In Jesus Name we pray. Amen.'
Let's join Flaywell in a resounding "In Christ Jesus Name"! Trusting God's power and presence. "For where two or three gather in my name, there am I with them" (Matt. 18:20). Keep praying and believing, everyone! 
for mental strength & protection. "For God has not given us a spirit of fear, but of power and of love and of a sound mind" (2 Tim. 1:7). Trusting God's shield. In Jesus' Name! 
Let's lift up 
