why does sb hate manvi much?

Im still trying to understand because Manvi is more childlike and Virat doesnt deserve to have fun i mean she likes Jeevika but for some reason she has a grudge against manvi, i dont care if jeevika younger then sb i hope she slaps her.I think she wants virat to be the serious type and be with s**tty girls lke maya instead of somone nice like Manvi.