y'all (gumrob haters) are wrong for simplifying gumball and rob's canon dynamic down to pure hatred. just like rob himself, it's nuanced, it's more complicated than that, and it changes over time!
in The Ex, for example, rob is relatively nice because he's guilty about the events of The Disaster/Rerun. at the beginning he clearly cares about gumball's feelings and handles the "breakup" delicately. then, even though he's annoyed, he maintains impressive patience throughout the day. even while crashing out at the end of the episode, the most violent thing he does is shake him by the shoulders. that's very tolerant and it shows that their relationship is not "one-sided" as many people say!
and then in The Spinoffs, even though he officially "hates" gumball again, his plan is so tame that it's not really evil at all. gumball probably never knew it happened.
the only reason he seems to revert back to "evil" after that is because his priorities change. in The Future he's rightfully very stressed, and it makes sense that he's willing to harm a few people in the name of stopping the literal apocalypse
basically, rob and gumball show too much mutual kindness and interest to actually hate each other. i honestly think that, when the situation is light and casual, they secretly enjoy interacting! otherwise, they wouldn't both go out of their way to meet sometimes