I don't think Seungho believes Nakyum ran away. He knows something happened, he noticed the marks on his mouth and his eyes swollen from crying. But he's confused and trying to collect his thoughts. He locked Nakyum up but he wrapped him in his robe and kept him warm by the fire. He wouldn't do that if he was trying to punish him. At the end we see him by his side waiting for him to wake up. That's a good sign.
I don't think Seungho believes Nakyum ran away. He knows something happened, he noticed the marks on his mouth and his eyes swollen from crying. But he's confused and trying to collect his thoughts.
He locked Nakyum up but he wrapped him in his robe and kept him warm by the fire. He wouldn't do that if he was trying to punish him.
At the end we see him by his side waiting for him to wake up. That's a good sign.