Episode 84 of "Felicity"
s04e22 Back to the Future

Felicity blames herself for Noel's death because he had survived the fire in the original history. Meghan suggests that she go to Korsikoff and undo the spell. Felicity doubts that this will work, but is willing to try anything. She convinces Korsikoff that she successfully used one of his spells, and follows his request by bringing in personal items from all of her friends. She tells Korsikoff about her friends, her life in New York, and her romantic histories with Ben and Noel. Korsikoff opines that she actually returned to the past to let go of Noel. He burns the items and conducts the spell. Felicity is afraid to go to sleep that night. She wants to undo the damage she caused, but is afraid of losing Ben. Ben pleads with her to try to forgive him in the future, and apologizes in advance. He says that he cannot live without her. Felicity wakes up the night before Noel's wedding, surrounded by concerned friends. They report that she developed a high fever and became delusional. Ben asks for forgiveness, using the exact same words as he had on her last night in the past. She agrees to take him back. Noel marries Zoe, and it would seem that everything had been a dream--were it not for the fact that Elena is now alive and back together with Tracy.