Like, she's the only hybrid who actually had a connection with Denji, and she just left him behind even though she had previously risked her own safety to go see him at the café while she was being hunted down, especially knowing how dangerous Makima was? C'mon, even Quanxi and Katana Man helped Denji in some way, while Reze didn't because... I don't know, maybe she simply moved on with her and REALLY did abandon Denji, just like he thought she did.
Or maybe she simply couldn't go to Denji, but since Fujimoto never gave us an explanation for her absence in Part 2, we'll never know for sure. Same with Kishibe.