I actually started laughing in the end. This was cruel for no reason.
I was actually getting on board, when she said she ain't giving up because it is not like the MC has started dating the girl he likes. I thought she was actually being strong and playful. I was like pumping my fist and being like with ya girlie! You cool AF!
But then the author made it depressing for no reason with her bookmark being destroyed. The giving up scene could easily been have positive.
If this was supposed to be MCs growth (which was already happening all the same), there was no need for Suzuri's depreso ending. She could have easily gotten a "I'm content that I actually tried, I have no regrets... (+Ve stonks)"
This ending being cruel like this just made it funny.