Apparently Daphne was a transmigrator from earth and og Daphne is dead so Daphne wanted to go back to her world she stayed away from the novel characters and eventually died but she regressed back into the story and tried everything to go back to her world but everytime she died she would always regressed back to the point she went insane and became the main villain(she regressed like 100+ times, tried killing off different characters to break the cycle)
At some point Daphne told ml abt the regression and from then he became aware of it as for mc he became aware muchh later so this isn't actually his 49th regression it's actually alot more
Long story short reason why Daphne was stuck was because mc couldn't let go of his love for her so her soul was stuck in the novel and she went insane after Hella regression and became the villain shit happened(like hella shit happened)and mc committed suicide for like 100+ regessions I think? He regression and immediately hanged himself and repeat
That was the grueling part for me

Just read like the whole novel summary in novel updates forum(because im broke ash)and the story's dark as hell just reading the summary alone alr leaving me flabbergasted the plot is GRUELSOME