I love the dynamic of Reigen being super guilty about realizing that he's returning Mob's feelings. Sure he totally exploits the kid in the work place, but he couldn’t possibly be some disgusting pervert, except suddenly he realizes what bullshit cognitive dissonance that is and spirals into self loathing because of it
Furthermore, what would it take for him to admit to Mob that he doesn't really know what's going on, doesn't have everything under control, and can't be the responsible adult spiritual master in the situation #ReiMob
Mob giving his powers to Reigen, and Reigen being able to use those powers to save Mob and the other kids, is suuuch an expression of love #ReiMob