I just feel bad for Fujio at this point. Him being deliberately left in the dark about all of this, despite the fact that Sakurai's reasoning for telling Hana should apply to Tsuki telling her husband.
You can tell that with how this mini-arc was handled, even with Yanagi seemingly teasing Sakurai about if he found her Mom hot (Even if it was light hearted, it's still weird she's joking about that, especially when the guy is her sister's fiancé and her Mom is still with her Father), that the author wants the oyakodon scenario to at least be "in the cards" and in the back of the reader's mind, even if he won't go all in on that scenario (at least in official material).
I just hope the author will give Fujio something to make up for how his character is being treated. Preferably an arc where Tsuki just let's go of her lusting over her daughter's fiancé (Don't deny it guys. Your comments are leaning too heavily in the implications for the plausible deniability card to be pulled), or even a chapter where her "overactive imagination" makes her think that a woman (maybe Ami?) is trying to steal Fujio.
I don't like the NTR bait in general, and I would much, MUCH prefer the former scenario to be what happens in the manga. But at least with the later, it'll feel like some sort of karmic retribution for what Tsuki is doing to her husband. If Tsuki would worry about Fujio being taken by some younger woman, it would maybe give her some perspective over how Fujio would feel about her delusions over Sakurai.
Even if you guys don't care about Fujio and just want the Mother-Daughter fanservice, it doesn't change the fact that the plot implications of this whole thing really does diminish the romance aspect of the story. If the author is taking the time to develop the story of side characters, like Kiri, then the author should end this pseudo-oyakodon subplot, ASAP.
This isn't me being anti-fanservice. I know that this is a rom com with sex jokes and I'm not being a prude here. However, when it comes to fanservice in a manga that want us to be invested in it for more than just T-n-A, there has to be a line you don't cross. If the author crosses said line, the story loses credibility as a romance, and the reader just views this as the author's fetish overriding the story (Rent-a-Girlfriend chapter 218, anyone?)
And for those of you still thinking that this Tsuki x Sakurai scenario should not be scrutinized like this and that it should just be treated as a joke, let me ask you two things;
1. Would you guys be just as adamant in defending this subplot and hoping for more "developments" if instead of Tsuki and Sakurai, it was Sakurai's Dad, Shirou, and Hana in this NTR-bait subplot? My guess probably not because a lot of you more than likely are inserting yourself into Shinichi's shoes when reading this manga.
2. If you found out your significant other (spouse, fiancé, boyfriend/girlfriend, etc.) was having the same mental scenarios about someone else that Tsuki is having for Sakurai, and even had a similar encounter in the bathroom as what happened these past few chapters, would you guys really be okay with that? Or would you label it as the borderline infidelity it actually is, or at least show SOME concern over the whole thing?
Bottom line, I don't like the Tsuki x Sakurai NTR-Bait plotline. It's objectively hurting the quality of the story. I feel too bad for Fujio and fanservice does not override these objections. Some things are just better left in doujins and not the official manga.