Women bond to a man sexually, partly because of wish fulfillment, an increase in Dopamine and Oxytocin levels associated with orgasm. Many women think that once they have slept with a man it means things are now exclusive; however, men do not necessarily subscribe to this thinking.
This is why it is SO IMPORTANT to have a talk prior to having sex to find out what this experience is going to mean for both of you and to make sure you are on the same page. If you are a woman looking for an exclusive relationship and he is a man who is not, then why would you have sex with him? You are putting your emotional health and risk and will end up getting hurt.