I'm assuming you meant why are girls hips wider than boys, and the answer is that girls hips widen in order to support a child if the girl were to get pregnant
to have intercourse with them
Gently
Women have broader hips so they can give birth more easily.
I have been told that after intercourse, when trying to conceive, it is helpful to elevate your hips(pelvic area) slightly for anywhere from 10-20 minutes.
Have sexual intercourse.
Bust, waist, hips.
To facilitate childbirth
Most females usually start hitting their growth at between 9 and 12 years. During this stage, hips broaden and the breasts begin to develop.
It is enjoyable and lovely
it feels good to them
it means he's attracted to you