the author/artist also made cesare charming after the regression, we can see he got a chemistry w/ MC, so it's understandable that people are disappointed and starts to ship them together
then the ML here is the super supportive (puppy) type of guy to MC, many readers see that as 'boring'. i'd rather have a boring guy than a charming azzhole tho
it's for the readers that self-insert, many wants the feeling of being pursued, it also gives off the "i can fix him" mentality, they thought 'oh maybe this time he will be good' 'he's so nice to me despite being bad to others, i feel special!'
i do self-insert sometimes but it's about revenge for me haha, i find it icky whenever cesare is shown and being attracted to mc so whenever he's shown i would just read quickly since i just want the story to move on

I HAD MF HOPE AND HE STABBED ME IN MY BACK HOLY NO BRUH