https://ayoti.in/blog/the-significance-of-colour-red-and-indian-brides/
From the Mythological context, Goddess Parvati and Devi Sita used to adorn their foreheads with sindoor. It is said that Goddess Parvati protects the husbands of those women who put sindoor and also wards off all evil spirits. A married woman is expected to wear the sindoor on her forehead till her husband is alive. There is another saying regarding the amount of sindoor that falls on a bride’s nose when her groom puts it on her forehead. It determines how much the husband will love her.