OK. First thank u for reading this. *secretly happy* This novel is an ABO and the omega is very popular and domineering and alpha is his fan and younger than him as he saved him when he was young. They share a dormitory because of different circumstances and alpha chases him. But he rejects him because his pheromone is too less and it can be fatal during marking even though he likes him. Then he nearly gets together with another alpha but leaves him because he is too scummy and ass and gets back with the previous alpha. Turns out the pheromone level of the alpha was suppressed by something I don't remember for him and actually has a high level of pheromones.
One of my favorite ABO with amazing smut https://www.novelupdates.com/series/the-short-story-of-shaowang/
The Short Story of ShaoWang https://www.novelupdates.com/series/the-short-story-of-shaowang/ Edit: Oh shoot didn't realize it was already answered sorry