We understand that you're feeling regretful about a decision made long ago, and it's important to process these feelings in a godly way. First, let's remember that God has a plan and purpose for each of our lives, and He can turn even our past mistakes into opportunities for growth and blessing.
It's natural to wonder about past choices, but it's crucial to align our thoughts and actions with biblical principles. In this case, it's important to remember that the Scripture tells us, "Do not be conformed to this world, but be transformed by the renewing of your mind, so that you may prove what is the good, well-pleasing, and perfect will of God." Romans 12:2 (WEB).
We need to address a few things in your post. First, remember that God's plan for romantic relationships is that they should be focused on marriage, a lifelong commitment between a man and a woman. Also, any physical intimacy, including kissing, should be reserved for marriage. We are called to honor God in our bodies and our relationships. I Corinthians 6:18-20 says, 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.
Moreover, it's concerning that you mentioned that you rejected his proposal because your friend liked him. It's important to make decisions based on God's will and not merely on human emotions or peer pressure. Proverbs 3:5-6 (WEB) says, "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."
Let's pray together:
"Dear Heavenly Father, we come before You in the name of Jesus Christ, lifting up our sister who is feeling regretful about her past decisions. We pray that You will grant her peace and guidance. Help her to align her thoughts and actions with Your will, and help her trust that You have all things in control.
Father, if it is Your will, we pray for restoration and healing in this situation. Guide her steps and help her to make decisions that honor You. Give her wisdom, discernment, and understanding. Help her to seek a Godly spouse and stay away from impure relationships. Protect her heart and mind in Jesus Christ.
We also pray that You will reveal Your purpose for her life. Help her to see that You work all things together for the good of those who love You and are called according to Your purpose.
Lastly, Father, we pray for her friends. We pray that they will also seek Your will and not be driven by emotions or envy. We pray for their salvation and sanctification. We pray for godly relationships and marriages.
In Jesus' name, we pray. Amen."
Remember, God is faithful and just. He forgives and restores. Trust in Him, and He will direct your paths. If you have not already believed in Jesus Christ then call upon his name. Romans 10:13 says, For whoever will call on the name of the Lord will be saved.
Prayer Focus: God, Thank You. Thank You for loving me. God, I ask You in Jesus’ name bless me with everything that I stand in need of and everything You want me to have. Bless me to know You in truth, fall in love with You with all my heart, mind, soul, body, and strength and never fall out of love with You. Bless me to have an ever growing closer stronger, more intimate relationship with You. Bless me with the love, desire, strength, and the spirit of obedience to always delight myself in You, seek first Your kingdom, and Your righteousness. Help and strengthen me God to always respect and obey You. Bless me to trust You with all my heart, acknowledge You in all my ways, and lean not to my own understanding. 
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