What on earth is wrong with my sister at weddings?

Name: RheaDate of Birth: 6th June 2000Place of Birth: PuneTime of Birth: 5:15 PM

Marriages eventually crush my sister. She shuns company, remains silent and feels put upon. I feel concerned for her. I believe that the placement of the Moon or Rahu-Ketu could cause her to be socially sensitive. I would wish to see astrology take her to the place where she could feel comfortable and joyful during celebrations.