Girls in general suffer from low self esteem. The majority of men do too.
It's simple, girls grow up feeling insecure and ugly, and when a guy shows them attention they feel flattered and happy. Obviously.
It's all about the hugeee emphasis on appearance, society's obsession with looking a certain way, the media etc. It's not exclusively Sikh girls, everyone has to deal with this and most people find it very difficult. Hence appearance related disorders such as BDD, anorexia, bullimia.