Landon felt a complicated range of emotions over being cast aside by Evelyn. Everytime she acted friendly with him when she had a fight with Edgar, but after patching the matter up with the boy, she started to ignore him again.
This made him feel enraged. It made him want to explode and shout at her. He wanted to know what he actually meant to her.
After everything, how is it that Edgar who mattered to her the most? It was him who always unconditionally listened to what she had to say, and he never argued with her.
He never ignored or hurt her. Edgar, who disappointed her countless number of times, still stays as the most important person to her. This made him feel a sense of betrayal.
Obviously, both of their hobbies matched, and he knew that Evelyn didn't appreciate how wild Edgar was. He was polite and well-mannered. He believed that he fit her criteria.