The Promise [Eren Yeager x Fem! Reader]

Four years ago, your best friend, Eren Yeager, confessed his love to you a day before he was to leave town with his father. He left you with a key, a kiss, and a promise, and you figured you would never see him again--until your first day of college when you see an all-too-familiar face. In what seems like a twist of fate, you two rekindle the love you had, though you quickly discover that there is more than meets the eye when it comes to Eren--and yourself.