Yea thats basically it. Souma thinks Noboru either hates or still loves Hayato, and respects that enough to try to get over Hayato. He doesn’t know about Hayato and Noboru conversation where Noboru basically gave his blessing. I get it, although, there is a difference between avoiding and running out with a random, looking for sex guy he just met.
The reason for trying to find another guy → He -of course- loves Hayato so much but wants to give up on him, so he tries to find love again in another man and forget him. As if he can do (¯―¯٥) He was only going to suffer more. Thanks to Yaoi God, Hayato didn't give up and stopped him (*˘︶˘*).｡.:*♡
Why did everyone start to hate Souma? It seems to me like he misread the situation. I guess he considers Noboru's feelings. Hayato doesn't like Noboru in that way though, plus I don't think Noboru would want to make it with Hayato anymore, but maybe Souma thought he is getting in the way, that's why he wanted to put a distance between him and Hayato? I don't know...