They may be in a relationship but they absolutely didn't stay together. That's why Mio drove Sakura home and that's why Sakura didn't change her dress to be what to wear at home while talking to fucboy. She didn't sit but stand and felt like she is at home. It's like she visited him to ask for his opinion then go home.
And it's the normal NTR plot that the victim will become the rapist's girlfriend or sex toy. NTR doujin plot has no reason for us to be considered. It is nonsense by itself. LOL
To be noticed, the vibe of chapter 133 and the vibe of chapter 134 are opposite. Chapter 133 told us the story will go for about 10 chapters but chapter 134 suddenly said Grapara will end in 2 chapters !
The events in chapters 133 and 134 did not align, despite attempts to link them. Even Mio’s behavior seemed odd. Did she shift from someone who had just learned about Sakura's story from having no meeting with Sakura for a long time to be someone who meet Sakura and fucboy regularly and close enough to say "what did he say to make you unhappy?" without mentioning the name of fucboy !? LOL
Was she putting on an act for Nagi in chapter 133, pretending she hadn't seen Sakura in a long time as well? Yet in chapter 134, she acted as if she saw Sakura and that fuckboy frequently to the point of being close with them. Why did she need to put on that charade for Nagi in chapter 134? What was the reason? LOL
Please give credits to
@diphuc1 who is the person who pinpoint Mio's opposite behaviors.
That's why we suspect the author of chapter 133 and 134 is not the same person. And we call the person ghost writer. LOL