Just want to point out that MC isn't going with the flow, he knew since chapter 3 that his father could betray him since he's just a backup.
Finishing the school is his top priority right now since it will grant him a standing, also being a member of StuCo could grant him further benefits.
Dad is kind of a dick, but he isn't a bad person, you can see he's joking about it and even call out Sakurai for it.
Also, both of them are health, so the pregnancy wasn't risky.