he tried to end his life and that was when he lost his memories -- this should be revealed in next chapter. with how his family lied to him about what happened to hakyung, didnt even mourn with him, scolded him for how he dealt with his disappearance, it's not surprising yoonsung was led into doing it. they all knew he was deeply attached to jiyoung. regardless of whether or not they approved of what he had going on with him, i think it was only right that they should've shown at least a bit of sympathy and understanding. that was the least they could've done after lying to him like that
he tried to end his life and that was when he lost his memories -- this should be revealed in next chapter. with how his family lied to him about what happened to hakyung, didnt even mourn with him, scolded him for how he dealt with his disappearance, it's not surprising yoonsung was led into doing it. they all knew he was deeply attached to jiyoung. regardless of whether or not they approved of what he had going on with him, i think it was only right that they should've shown at least a bit of sympathy and understanding. that was the least they could've done after lying to him like that