Harry: Harry wouldn't leave you alone. He kept giving you things and apologizing and following you around like a lost puppy. You decided to forgive him, mostly to get him to shut up.
Ron: Ron handed you your favorite flowers and told you he would always trust you from now on, so you forgave him.
Fred: Fred told you how he wasn't pranking anyone anymore. You felt bad. You knew he didn't mean to hurt you, so you forgave him.
George: George wouldn't ever be at the store anymore. Why? He'd always be with you. You realized he did care about you and you forgave him.
Neville: Neville showed up at the Hufflepuff dorm with flowers and candy and begged you to forgive him. You sighed and nodded. Neville still doesn't know exactly what he did.
Draco: Draco kept telling you he wouldn't argue with you ever again. You didn't believe him at first, but when you started saying the most stupid things and he agreed anyway, you knew he wasn't lying and forgave him.