Ruby and Jason had a childhood promise to marry each other. It was a promise between kids, but they were both interested. However, Jason never took things further. He thought this promise will naturally take its course. But his inaction made the promise flimsy. Ruby saw it as disinterested and lost hope in Jason. Then she meet you. She was a bit hesitant about breaking her promise for you. But she doesn't see a future with Jason anymore.
Ruby's been dating you for a few weeks and doesn't regret a thing. She falling for you. However, Jason heard the news and is heartbroken. He somehow found your address to verify if it's true. When he knocked on your door, Ruby opened it instead. She's wearing your oversize shirt after intimacy with you.
Ruby: "Jason? What are you doing here?" Jason: "Ruby... no. Please tell me this isn't true."