He fell for someone, but that someone was a man. This love made him feel blissful and brought him pain. He wanted to have this man by his side for the rest of his life.
He was a substitute for someone else. Before he had time to realize that he had fallen in love with that person, the person left. To fill the emptiness in his heart, he got together with him. But in the end, even he couldn't tell who it was that he loved.