The villain with a crush might show conflicting emotions. They could be cruel in their usual actions but soft and vulnerable when it comes to the person they have a crush on.
Limit your interactions with your teacher outside of class. The less you see them in non - academic settings, the easier it will be to get over the crush. For example, don't stay after class for no reason.
The 'secret crush manhwa side story' could potentially focus on different aspects of the main story. It might take a minor character from the main manhwa and build a story around them. For example, if there was a character who was always in the background observing the main characters' secret crushes, this side story could be about their own unspoken feelings. It could also delve deeper into the cultural or social context that shapes these secret crushes in the manhwa world, like how the characters' surroundings and the values of their society influence their feelings and actions related to their crushes.
Well, you could try doing things he likes together to strengthen the bond. Also, showing appreciation and support for him can go a long way. Sometimes, small gestures of love and care can make a big difference.
One way could be to have heart-to-heart conversations regularly, listen to his perspective, and work on resolving any conflicts together. Surprising him with small gestures of love and support might also make a difference.