Event - Romance Saga
It's not that Ziran wanted to ignore her emotions willingly. But he was uncomfortable. Deeply uncomfortable with the idea that she doesn't want to stay close to him.
Although it would hurt, he is more than willing to let go of her if she already has someone in her heart. However, if that's not the case, then he isn't willing to give up even before trying. He was just 16, burdened with the sudden decision of his father to leave the kingdom.
Yes, his elder brother had always been there for him and Steven as the protective rooftop, but that never meant he didn't have any duty to fulfill. His mother was a warm source of comfort in his childhood. He could never completely heal from losing her. And then watching his elder brother shoulder all the tough responsibilities at such a young age made him harden his heart.