Why is this girl playing hard to get?

-This question is really for a buddy of mine. I was on a double date with my buddy, He brought me along to meet a friend of a girl that he knew. We were suppose to got watch a movie but things got in the way so it got cancelled so we made plans the next day to go over the girl house and watch a movie there instead. When we went, they had a jacuzzi, so the girls asked if we wanted to get in. So of course we couldn't refuse. When we got in, we drank a little and I started making out with her friend. Ok the whole night my buddy's girl was very talkative. I think she had ADHD or something. She was talking non-stop. I started making out heavily with her friend and my friend and his girl were in the other corner of the jacuzzi staring at us like little kids. I tried to help my friend out and told him that we should have a competition and all. Even my girl tried to help out. But that girl would kiss my friend. She kissed her friend but not my buddy. Before we got in the jacuzzi she was talking about how they've been with assholes and wanted a nice guy and my friend mentioned this to me pretty often before we met wit the girls. Now I am a nice guy but and stayed quite the whole night as well. That was only because the one girl was talking none stop. But things got really heated between me and her friend in the jacuzzi, afterward I took her friend to her bedroom because she seem really tired and was falling asleep on the dining room table. I wasn't planning to do anything I just put her to bed but when I got in bed, she just came at me, so I really had no choice and had sex with her that night. I know this feels like a one night stand. After we were done, I told her I was leaving and gave her a kiss on the cheek and she was just like whatever. So anyway, I didn't get the girl number but I don't really care. Nothing happend for my buddy and I felt really bad and I asked him how is he doing with this girl? and he was like she has been ignoring him a little. Did I screwed this up for my friend by having sex with that girl? I feel really bad because I know that he really like this girl.This girl is not exactly playing hard to get. She is just being cautious because guys probably used her just like u used her friend. She doesn't want to be committed to your friend until she knows that he isn't a player and isn't the type to walk away and leave her. I think in a way, you did mess things up for your friend because obviously the girl you slept with would go tell her friend what you did, and that would make her think that your friend is the same way and may do the same thing to her. She just doesn't want to be used, and frankly there is nothing wrong with that. When it comes down to it, guys only want one thing, but this girl (most girls) won't put up with that.well , I don't think you ruined anything . it's honestly not your fault that she wasn't showing any affection . she should've know wht she got herself into when she invited you guys over , I'm sure she knew he didn't just wanna be all bored & unentertained . But she insisted on running her mouth . That's what ruined it , yeah and tell your buddy that if she really wanted to be with him she wouldn't do all of this . & since you said he is a nice guy , there are plenty of women that's into guys like that . And tell him to tell that girl if she like him tell him & if she doesn't he needs to move on! one more thing make sure you tell her she needs to learn how to shut the **** up!