I agree with you, but you got to remember, Shingo broke up with him, but then he realized he shouldn't have. So now he went to go fix his mistake.(๑•ㅂ•)و✧
I agree with both of y'all but I do feel the need to mention 1) Shingo wasn't technicality the one who broke up with him, it was more like a mutual thing where although Shingo was the one who brought it up it was agreed to by both of them. 2) It isn't that Shingo "realized he shouldn't have" broken up with Keiichi, it's that he realized that he still loved Keiichi. And 3) Saying that "he went to go fix his mistake" is invalidating Shingo's insecurities by insinuating that he made a mistake in feeling the way he did about the situation. Keiichi actions with regard to the Angelo(?) character made Shingo feel insecure. Keiichi not further explaining the situation and not trying to make Shingo feel secure, add to this the scent issue further exacerbating the situation and making Shingo feel worse, Shingo is not wrong for feeling insecure, there is no mistake to fix because he isn't wrong for feeling this way.
In the end, it isn't Shingo going to "fix a mistake", it's him realizing he loves Keiichi enough to overcome his insecurities (mind you without any help from Keiichi himself, although being a part of the cause for the insecurities)
._. Damn you bitter sweet feels. I'm glad its resolved but pissed off that Shingo is the one who had to plead for Keichii back. That bastard.