I don't want the manga to end T_T please god no :‹ I want it continue with them in a un...

We're still a long way from over, I bet. Nakano's felt guilty about her powers before, and that guilt would increase two-fold if they get together. Part of the reason Toda likes her is because he thinks she's able to read his expressions, but in reality it's just her mind reading ability. She's expressed concern over this before, so if they start dating then that guilt would start bearing a huge weight on her heart.