You are a lighthouse and day & night you vibrate and send energy to people around you no matter where they are on this planet they are. They can unconsciously feel this energy and then decide to react or now. Like a Phone call, for example, this situation happens to us several times per year.
What is she getting out from it? Remember that for them sex is more a hassle than fun. Some girls really love sex, but most are just using it to get something in life. She is giving you sex so she can get something back. What do you my friend give in return for sex?