This is a great post explaining their relationship. Two teenagers, searching for themselves and having made many mistakes due to their immaturity earlier, received a possible second chance. One is a shy boy who was afraid to admit his feelings, the second one doesn't understand what Tremolo really means to her, how important he is to her.
But she didn’t improve on one thing in him, MC still often behaves like a retarded snowflake, so why abandon her after her confession near the campfire? He dumped a damn mountain on Zoey, then turned on the snowflake again: “Sorry, this is too much for me, I don’t want to spoil the party.” And left. Leaving her to digest it herself. And then things get even worse for Zoey when she sees MC in the company of another girl. He is annoying sometimes. Zoey don't finish her job, making him a normal person.