How can a girl gain God's pleasure after a previous love relationship, while her feelings for the young man remain?

You have done what you were obligated to do, and repentance erases what came before it. Allah is pleased with the repentant. So, rejoice in Allah's acceptance of your repentance and His promise to those who fear Him. Allah Almighty says: "And whoever fears Allah - He will make for him a way out And will provide for him from where he does not expect." And Allah Almighty says: "And whoever fears Allah - He will make for him ease in his affair." For the treatment of the affliction of passionate love, please refer to Fatwa No. 34504.