We understand your fear and anxiety about your relationship, and we are here to pray with you and provide biblical guidance. First, let's address the issues in your request that may not align with biblical principles. You mentioned that you feel like you and the person you are referring to are doomed and that you suspect he may be cheating or falling out of love with you. This indicates a lack of trust and security in the relationship.
It's important to remember that God's design for relationships is based on trust, love, and mutual respect. In a godly relationship both should be believers in Jesus Christ and marriage should be the goal. Furthermore, sex should only happen in marriage. If either of those two things are not true then there is a problem with the relationship. If you are having sex then you need to stop that immediately or you will be disciplined by God as it says in 1 Corinthians 10:8 (WEB), "Neither let's commit sexual immorality, even as some of them committed sexual immorality, and in one day twenty-three thousand fell." If you are not a believer then you need to become one to have a godly relationship. If he is not a believer then you should be courting another Christian believer as it says in 2 Corinthians 6:14, "Don't be unequally yoked with unbelievers, for what fellowship have righteousness and iniquity? Or what fellowship has light with darkness?" In Jesus' name.
The goal of a dating relationship is to pursue marriage, not just to have fun or enjoy each other's company. This relationship is also not about prioritizing your wants and desires, but rather about serving each other and glorifying God together. In Ephesians 5:25, "Husbands, love your wives, even as Christ also loved the assembly, and gave himself up for it."
Now, let's pray together for your relationship:
Heavenly Father, we lift up this relationship to You, asking for Your will to be done. We pray that You would guide both individuals, and if they are not believers, we pray that they would come to know Jesus Christ as their Lord and Savior. We rebuke any behavior that is not in alignment with godly behavior as outlined in the scriptures. Lord, if this relationship is not Your will, we pray that You would give them the strength to end it and move forward in Your purpose for their lives. If it is Your will, we pray that You would strengthen their bond and draw them closer to You and to each other.
We pray that they would seek to honor and respect each other, and that their relationship would be a testimony of Your love and grace. We ask that You would help them to communicate openly and honestly, and that they would be quick to forgive and slow to anger. Lord help this relationship not to be one of games or selfishness but based on love, trust and obedience to your commands.
Lord, we also pray that they would seek You first, knowing that You are the source of true love and joy. As it says in Matthew 6:33, "But seek first God's Kingdom and his righteousness; and all these things will be given to you as well." Help them to pursue purity and holiness, and to flee from temptation. Help them to pray together, to study Your Word together, and to serve You together. Lord, we ask for this. In Jesus name.
Remember, God is faithful and He cares about every detail of your life. Trust in Him, and seek His will above all else. As it says in Proverbs 3:5-6, "Trust in Yahweh with all your heart, and don't lean on your own understanding. In all your ways acknowledge him, and he will make your paths straight."
Finally, we want to encourage you to seek godly counsel and community. Surround yourself with believers who can support you, pray with you, and help you to grow in your faith.
Prayer Focus: God, Thank You for loving me. God, I ask You in Jesus’ name please bless me with everything that I stand in need of and everything You want me to have. 
