TLDR Ryota comes to his GF Yuka's place demanding to know why she avoids and told him to break up, there she tells him the reason she cheated on him the day she joined the university's circle where she got drunk and seduced by a playboy Hiroki, unfortunately for the BF it wasn't just a one time thing, despite being childhood friends and a couple they never did have sex but Hiroki easily got that from her and became a sex relationship where she always available at his whims. He realized at the end he did wrong holding back on making sexual advances on her thinking she didn't like pervert things, that's why he lost her
After finishing her confession she repeats she wants to break up with him, then tells Ryota he's a good person but she's a bad person and that she sorry. He has no choice but to admit the results now.
Base +22, Nikita78 +24, your_name +6, ehformycollect00 +6
This is social norms and talk no jutsu being used here. As if girls don't like sex as much as men do. If she wanted to have sex she should've just said that. It's a 2 way street. Side note at least she tried to break up with him and admit she's in the wrong.