The top and bottom were a couple back in school, but later broke up because the top's parents got in the way. The top misunderstood the bottom and went abroad to forget him. When he returned, he saw the bottom and realized he still loved him deeply. Thinking himself pathetic, he went out of his way to humiliate the bottom. The bottom is extremely insecure, and later, for certain reasons, his mind becomes impaired. He forgets many things, but remembers every little moment he shared with the top perfectly clearly. Later, the top learns the truth and is heartbroken, but the bottom never believes that the top loves him. Heartbreaking in the beginning, then sweet and fluffy later. Definitely a happy ending. Note: The top wasn't born gay. At first, he thought the bottom was a girl.
The writing is good, keep up the good work~