There is a lot of speculation but I think we can all agree that the story as of 131 is a mess.
Plot holes abound and panels are used to obfuscate the plot rather than convey it. Characters react in a stupid way or not react at all when it's clear they would.
It's never good when the reader has to make baseless assumptions on what happened behind the curtains for a story to make sense.
The only "advantage" resulting from this mess is that the story is now extremely open ended. She can make it look like anything.
Spitballing some scenarios that could happen (some of them only if the mangaka loses her mind):
- fuccboi truly loves Sakura and just want to be with her
- fumi and fuccboi colluded to split Shikura
- fuccboi played the blonde so she would help him nail Sakura
- Shifumi end up together and Sakura ends up alone
- fuccboi marries Sakura but she longs for Shinobu
- Shinobu ends up alone but highly successful
- Sakura learns the truth, dumps fuccboi and chases Shinobu
- Sakura learns the truth, doubles down with fuccboi so that Shinobu can move on
- Sakura learns the truth, dumps fuccboi and degrades herself as penance
- Fumi starts dating Shinobu and gets pregnant
- Fumi stops Sakura from getting back with Shinobu, clearly NTR'ing him from Sakura
- etc...
Some of these are more nonsense than others but any of these could happen from the clusterfuck of the last 5 chapters.
I was never invested in this story because I don't hate myself but I have to admit that I can hardly wait for 132 just to see if Katsura Airi digs herself of the hole or further punches her own tits.
What a time to be alive!