Everyone seems confused so let me help u out. YES they're not together but it's an a** move on his part. 
So Won is only doing this and trying to forget about him because he's fuc**** STUPID and indenial. The fact he won't accept he feels something is hurting her in turn and that's why she's on a date, attempting to forget how she feels, because she thinks he doesn't feel the same.
Meanwhile, he IMMEDIATELY jumps to bed someone else after taking her virginity? It's shi***. It's EXTREMELY shi***. He's dense and it's frustrating. She wouldn't be doing this if he communicated, but we all know in these stories that's basically impossible. 

People are allowed to get frustrated, upset and hateful if they want to. No one reads a romance story and reads erotica between the MAIN CHARACTERS just to get flashbanged with the ML sleeping with another woman, especially when you're hopeful of their relationship. He's doing all of this because he's being dense and indenial. OFC PEOPLE ARE GOING TO BE MAD. NO ONE READS THIS TO WATCH THE MC'S SLEEP WITH OTHER PEOPLE??? G**.