What's dabda?I've been hitting on this for a while.
The first arc was Sousuke's negative character development arc. By believing in a lie that blinded him from the World, Sousuke ended up in a worse place than the one he started. Mainly, until the end, he believed Rika was "stolen" from him, so when he cornered Shingo, and we learn Shingo was approached by her, it finnaly showed what the truth was. She escaped and left him in a dire predicment.
This arc will be his positive character development arc, he will break the lie that's her image, and end up in a better place than the one he started with, with Iwabuchi being a potential stepping stone to that goal.
In both instances( this being also a conjecture of the current affairs), i see a DABDA like situation, where people underestimate Sousuke's mind. During Shingo's pursuit, Shingo thought Sousuke was in anger/denial. Iwabuchi MAY BE thinking Sousuke's bargaining for Rika's sake. In both instances, Sousuke's shown he's already past acceptance, and just wants closure. So maybe the party will shock him, but not affect him the intended way.
Sousuke has to be ultra pro Max blind to not be able to see rika