first time talking to a girl..

so my best friend hooked me up with this girl. i'll refer to her as A lol. so A knew that i was straight, and that she would be the first girl i ever talked to. when we went on a date we instantly clicked. everything felt natural. we've basically have been seeing each other every weekend whether we were hanging out alone or with friends. we've been open with each other about our past experiences, and she's revealed how she was in a 6 year long relationship. she would mention her ex a lot when we would speak on certain topics, but it never bothered me. from the start we spoke so freely about everything so we were all ears to one another. a few times i've noticed her being standoffish towards me. her responses to me would contain a lot of attitude. when she would act that way i would just brush it off. i wouldn't really dwell on it because this situation is still fresh. just to throw this out there, we spoke about how we weren't getting into anything serious. we were just going with the flow. so whatever happens happens. two days ago she's acting standoffish once again,
and this was right before my best friend and i were going to meet her at her house. when i take notice of her actions i keep quiet. we start drinking then she starts talking to me more, and acting affectionate. just noticing me more. as the night goes on we end up in her bed. we're kissing, and touching then she lays on top of me, and begins talking. she says "don't become attached to me, even though i know you already are". this threw me off a bit because it was so random. then she continued on "i know i'm mean to you, but it's because i'm pushing you away. i'm not good for you, and you shouldn't fall for me. i can see you being the girl that i can fall in love with, but that's just not what i want right now. i know that this would never work because i'm gay, and you're straight. since i'm leaving i don't want you to wait for me. i want you to live your life" then she ended up giving me head, and then we fell asleep. i'm just so confused because now i don't like the shift in her actions towards me, and now that that conversation transpired it leaves me conflicted. i don't want to be pushed away by her because i do wanna give us a chance. when she mentioned she was leaving she was talking about her leaving to the army in a few months. i just want feedback on what it is that you think i should do. i really enjoyed how things were going, and yes i like her, but i knew what the set boundaries were. i just didn't think it would get deep like that. do you think it's her feelings that she's pinning on me so she doesn't have to deal with it?