So basically:
if the series ends in 5 chapters then that gives higher chances of Fumi and Shinobu getting a happy ending, however as someone just pointed out, author can still asspull Sakura finding out the truth in these 5 chapters and finding her way back to Shinobu.
If the series doesn't end in 5 chapters then that does give Sakura more room to feel "sad" and go back to Shinobu, again, whether or not Shinobu takes her back is a different matter, I would hope he doesn't but quite frankly nothing would surprise me at this point.
At the very least, I want Sakura to find out the truth, I want blondie and ikemen to abandon her or just let her fall further into corruption for their own gain while Sakura realises what she lost, considering how this chapter has gone, in how Shinobu has accepted the breakup and is trying to move on, whatever happens I think the chances of Shinobu taking Sakura back are low and consequently, the chances of Sakura getting some consquences are high.
Keep in mind everyone who committed wrong in this series got punished, director got stabbed, that one guy whose name I forgot got hit in the road (still survived but injured) and so Sakura can absolutely get punished as well and I think I know the perfect punishment.
Shinobu was truly not cheating on her before but by not hearing Shinobu out, by falling right into playboy's lap and letting him fuck her passively, she has essentially created a self-fulfilling prophecy where Fumi has swooped in and soothed Shinobu's heart, I think the best thing Sakura can hope for is that Shinobu forgives her but doesn't take her back, that's the best ending for us and for Sakura (not that she deserves it) but again, we gotta stay on our toes with these next few chapters, because if this series doesn't end after 5 chapters, anything could happen.