So to recap:
The movie Shinobu was doing was successful with Fumi stripping and kissing for it
This elevated Shinobu to greater heights
Timeskip
Fumi comes clean after things between her and Shinobu didn't work out (what a shocker)
Sakura is the actress in a new film that Shinobu is involved in
Sakura is no longer with fuckboi and is wearing Shinobu's necklace
Final scene is Shinobu and Sakura handholding while they smile at eachother.
It's a pretty expected KA ending all things considered, the main takeaway being that whether Shinobu is a cuck or not, him and Sakura are on good terms again supporting each other.