Responses
So it seems. Two times with the fiancé, but I'm not sure, maybe the novel it's more clear.
I don't think he did again, the thing in the extras (the novel) was someone trying to sabotage Shao Qun. After the first time and everything that happened he just went full obsessed mode but he doomed himself to walk on eggshells the rest of his life afraid of Chengxiu leaving him, that's what it looks like in the rest of the extras years later when they live together.
Does he cheat a second time later in the story?