Realationship advice

[girltrouble1234]

So I have been dating this girl for about a year and things are ok. I don't know I love her but she has made it clear she loves me. She is a good "home body" and a driven person. I am not too attracted to her, but I don't really mind too much. By 'home body' I mean that she is good around the house, cooking, laundry, cleaning, etc.

She is a grad student, works hard and is 23 going on 24. She recently moved 40 min away and we don't see eachother that much anymore.

When we see eachother I am not really excited so much but just think, a friend is coming in that I can have sex with and hang out with her and her friends.

Anyway, she was gone this weekend and I ran into a old friend. She is 19 and is the younger sister of one of my highschool friends. (i am 21 ftw). She is exciting, attractive, friendly...etc. She hit on me at the bar and I kind of went with it. Ending up going back to her place and playing drinking games after bar close. Got drunk and stayed over. Made out and got to 2nd base but I stopped things before they got any further. She definatly made it clear I could do anything I wanted, but I stopped non the less bc of my gf. She didn't know I had a girlfriend but ended up finding out the next morning. Long story. Any way she seemed pretty cool with it and still made it clear she wanted to hang out more. She called the next day I and I got the butterflies talking to her and that is a feeling I havent' had in a while.

So the next night she calls and wants to hang out. (already fully knowing that I have a gf). I got excited and we meet up at one of my friends parties. I meet up with her and we walked over there. Talked the whole way, played beer pong, and when we left I walked her home. But we walked by here place and instead just walked around a bit and talked.

Now here is the curveball. We start to talk about "how hard it was for her to be single and that there was this boy that she is interested in, "louis". WTF? So now I am thinking that she is one of thoes people that just doesn't want to sleep alone on the weekends and I was just the guy for that weekend. The funny thing was after we got done talking about Louis she invits me up. We hung out but I just couldn't stay. So I say I gtg and made up some [censored] reason and she says stuff like. "wow i just got rejected." So wtf.

Do I stay with my gf bc this was just a random thing and I don't exactally know the motives of the mistress? Or do I break up with the gf bc I feel bad for "cheating" and I could have a shot with this other girl, girl that gives me the butterflies.
She is sexy.


P.s. can't stop thinking about the mistress.
P.s. Was drunk the whole weekend, as was she.
P.s. My gf was in another zip code.

P.s bc I don't know the rules here in OOT and usually post in bbv.

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Edit/MH: Photos removed at request of OP.