Wait so why is the uke such a dick to the alpha? It seems he covered him with his pheromon...

The issue is that because Su ah kept covering Uke with pheromones while he was young, uke never got the chance to build up his tolerance to regular alpha pheromones. Now even regular alpha pheromones causes him discomfort

Also uke sees being an omega as a setback. He sees omegas as weak and so he sees himself as weak which makes him angry. I don’t think he was actually angry at su ah just lashing out because of his predicament. And it got worse when he realised he is somewhat weaker because of his intolerance for other pheromones due to Su ah