<human>: Give me the gist of the text in a nutshell

Girl and I hung out for the first time. We got ice cream and then made out in the back of my car (with lots of touching in other places).She also said she "couldn't wait to give me a bj". Before we made out she told me she was obsessed with me. Next weekend rolls around and I ask her to hang out again and she says she is busy. 2 more weeks go by and I don't ask her to hang out because I am busy. I find out she fucked another guy (not sure when but within the last few weeks). I feel hurt even thought I shouldn't. We never put a label on what we are. She has hinted that she is fine with having multiple sex partners. (Told me about some book she read where a women cheats on her husband and fucks a bunch of guys, and she said she supported the women). So what I'm wondering is how do I have sex with her and not get to attached.? I'm dying to get laid here but she clearly doesn't want a relationship.
<bot>: made out with a girl. She has sex with a different guy. I feel hurt even though I shouldn't. How do I have sex with her without getting attached.?