We are truly sorry to hear about the struggles that your loved one is facing. It is encouraging your desire to help him. First and most importantly we need to pray in the name of Jesus Christ for his struggles. It is only by the name of Jesus Christ we have access to God.
Before we proceed, we must note using the term "He" instead of "husband" or "fiancee" indicates the relationship is either not aligned with biblical principles regarding marriage or it is a relationship where marriage should be strongly considered if both of you are Christians. In either case, we would strongly encourage considering a path of courtship leading to a biblical marriage. God has designed marriage to be a lifelong commitment between a man and a woman, and it is within this framework that we can best support and help one another.
Let's turn to the Word of God for guidance. The Bible tells us:
Be anxious for nothing, but in everything by prayer and supplication with thanksgiving let your requests be made known to God. And the peace of God, which surpasses all understanding, will guard your hearts and your thoughts in Christ Jesus. Philippians 4:6-7 (WEB)
For God hasn't given us a spirit of fear, but of power, love, and self-control. 2 Timothy 1:7 (WEB)
Cast your burden on Yahweh, and he will sustain you. He will never allow the righteous to be moved. Psalm 55:22 (WEB)
Let's pray together:
Dear Heavenly Father, we come before You in the name of Jesus Christ lifting up this man who is struggling with intrusive thoughts, panic attacks, and anxiety. We pray that You would comfort him, give him Your peace, and remind him of Your unfailing love. Help him to cast his burdens on You, knowing that You care for him.
We also pray for the one who submitted this request, that You would give them wisdom and discernment in how to support and help. Guide them in their relationship, and if it is Your will, lead them towards a God-honoring marriage.
We ask this in the name of Jesus Christ, for it is in His name that we have access to You, Father, and by no other name can we be saved. We ask all of this by the name and authority of our Lord and Savior, Jesus Christ.
Amen.
We encourage you to continue supporting him through prayer, love, and encouragement. Remind him of God's promises and presence. It might be beneficial to seek professional help from Christian counselors or therapists.