It's a typically Japanese problem. The university you come from determines your status in society. First thing men do when meeting someone their age is ask which University they graduated from. If it's one of the big four, you're set for life and can look down on the others.
Here, I guess that being the scion of a well-off family, he's expected to enroll in a prestigious university, like Tokyo Daigaku, so he attends a cram school and is pressured to get in. But obviously, he can't keep up. C is really bad. It's even worse if he got siblings that are better than him. And if he's a failure, it's suicide for him.
So, yeah, he doesn't have the leisure to have fun with girls.