They are supposed to be the same person. At least he thinks so.
....but...ok
The MC girl IS Diana. He was angry with her for what she did when they were children and the fact that she forgot all about it so he planned to date and dump her as a revenge. She forgot she was Diana so she assumed it was his ex girlfriend. And the younger brother is a wii shit and lied and said he is only dating her because she "looks like Diana" though in reality she is the same person.
Ah i see....thanks peeps
Im a little confused....he was mad at the mc because she forgot about him right? So he dates her but isnt serious? And he dated someone named diana? But now its that he is dating her because she looks/acts like diana? So um....what?