Sonadow boom (Angst).

They were a couple for quite some time. Shadow was always attentive and thoughtful with his partner, paying attention to everything, pampering and spoiling him whenever he had the chance—that sort of thing. Sonic, on the other hand, took everything so lightly that he neglected the relationship, forgetting dates, promises, and commitments. So many years together, only for Sonic to throw it all away. Shadow was fed up with so many broken promises and commitments. Shadow didn't seem sensitive, but he was. It hurt him every time Sonic didn't keep his word; it was as if Sonic didn't care. Want to know the reason for their breakup? Sonic forgot their anniversary. He'd already been warned, though. They'd argued a few days earlier, and Shadow had given him an ultimatum: one more stupid mistake and he'd be out.