It's very hard to always be the one to offer yourself. Some men are afraid that women say yes, but mean no. Men don't like to pretend that they always want sex. Men are afraid of being rejected and turned down. Women Women are socialized to believe they should always go along with what men want, in spite of what they want.
Many women are afraid of hurting men's feelings.
Some women don't like pretending that they don't want to have sex. Men and Women Do want friendship with each other. Sometimes the friendship includes sex, sometimes it does not.