Sorry but did he grape her…

Yeah. this shit is a lost cause

not exactly that. She consented because she realized she was still in love with him despite her efforts to convince herself she wasn't. Manga did a bad job of explaining it compared to the novel. Manga makes it look more like she was guilt tripped into accepting it or forgiving it rather than her going "My rejection is making him so sad" > "It shouldn't bother me that it does" > "Oh, it bothers me because I really am in love with him and I want to be with him even though he loves someone else"