I think it's because her name is jhanvi and her husband wants to marry another Om will draw a parallel to what happened with his mother and hence stop the wedding. Thereby saving Gauri as well
Janvi Thakurain will be mistreated by Kali Thakur and Om will try to save Gauri from his clutches because he understands the pain his mother has gone through and this other Janvi will have to suffer if people like Tej and Kali get their way!