I think they didn't need a big character development, they just needed to change their relationship and that happened in the end (the way there could have been easier I guess). But compared to BJ Alex this relationship was way less toxic from the start, so I kinda think it's enough ╮( ̄▽ ̄)╭
I actually loved the side story, don't know why people hated it ╮( ̄▽ ̄)╭