The main problem with addressing Iwabuchi as a culprit/mastermind of this whole ordeal is, well...red-herring yourself into a Shiratori-like scenario( where everything pointed out to a possible blackmail to affair against Rika's wishes) on a Shingo-like logic( where Sousuke thought vehemently that Shingo lured Rika into having an affair, only to find out it was the opposite, and worse, Rika ran away after).
Also to point out, when Rika made her lascivious expression, Iwabuchi bit his lip. It doesn't seem like he's holding her down, or at the very least, controlling her fully. And if he is, and used her to develop Shiratori and Shingo's bussiness, then how much "holding" does he have, allowing her to marry and have a child of her own, in the meantime?
Moreover, momentaneously disregarding theories, If Iwabuchi had a hold on her, and considering his name, money and influence on the night district, why'd he need money from Shiratori's and Shingo's bussinesses? Likewise, if he was the one who needed/wanted Sousuke's evidence of adultery, why wasn't he the one who contacted Misato directly, since this would make it seem like Rika wasn't involved, nor would there be a reason for Misato to find it strange and have second intentions?
There's also the matter of the contradiction. If Rika seriously wanted to get away from Iwabuchi, being as smart as she is, she knew it was impossible. Unless she actually managed to be "let out" by him, in which case, having a "happy family", why'd she make the jobs with Shingo and Shiratori?
Or is the point that, she managed to run away, got caught and forced to do the jobs against her will? If so, why did she say, in chapter 10, "thanks to that person, i can still have some fun"?
As much as objetification is involved( i may be nitpicking on that), Iwabuchi potentially seeing her as a big source of income may be on the same level as Shingo seeing her as his golden goose of sns attraction. Both which are a little lower, but truer, than what we saw through Sousuke's eyes, as he constantly refuses to see Rika for herself and sees only the image of his adored wife.
But hey, if we're going through a Shiratori-Shingo-like story, why not believe that Iwabuchi made it big in the night district partially thanks to Rika herself? Just Saying...