My friend's dumb girlfriend... I'll end up sucking her

(non-real story, fully fantasy... for now) I'm Sebas, so you can get an idea of what I'm like, 18 years old, 1.80 meters tall, coffee-colored eyes, skinny but with a few months of gym and a cock of about 20cm... one day I was taking a break in the square with a couple of friends and girlfriends, including Martu, 18 years old, around 1.70 meters tall, trains a sports team so she has a toned body, small tits but an infarct booty... while we were chatting nonsense, the idea came up to go to a graduation party on a Wednesday, her boyfriend doesn't like going out much so he didn't want to go and the others couldn't. so I ended up with a couple of friends alone one night in a pre-party at the house of one of them, without any of the guys and only 4 girls, including Martu who was wearing a short skirt well fitted to her body and a top cut out well showing those precious tits, between glasses in the pre-party we were all getting drunk, the music was Bonner and a scene that's stuck in my eyes, Martu dancing wild in front of me, I couldn't help but look at her beautiful ass while she danced and her skirt rose up showing the black thong well inserted into her bootyI was sitting in the chair scratching myself quietly while enjoying the show until I grabbed her hand and got up to make her 'dance' with me. I took advantage of the golden situation I had and stood up, holding her all the way while dancing closely to me, hands on my hips, and every time she leaned against me more, until the moment I didn't want it to arrive, the Uber was at the door, I already had a hard cock and grabbed my pants and got out, we went in the Uber and while driving, I kept pulling her saying 'you look beautiful today' 'I loved how you danced with me' the typical ones that never fail.We arrived at the bowling alley, everything still half asleep yet, bored but the girls were having fun in their own way, I on the other hand was getting bored to death, then I got up and went to take a few laps, ate some cutie or two and came back where they were, Marti was still really drunk and jumped at me to hug me, I took advantage and put my hands on her back, close to her Booty, going down slow to feel the terrain, she wasn't saying anything so I kept going with my hands halfway up her terrible ass when a song by Joaquín started playing that she loves, it made her stop hugging and start dancing, I got closer from behind and whispered in her ear I love how you danced before but you're really boring, don't pretend to be good, the competitive girl who doesn't like losing me says: No? You didn't see anything, look at my ass on the cock and it's pulling me to dance like nobody else, seemed professional the slut, never had anyone danced with her cock so well, or maybe that's why she got hot, I don't know but good, question is what gets my cock hard and I start putting my hand in her Booty while dancing and the slut doesn't stop until she turns around to look at me and I pull out her mouth, the slut instead of taking it from me because I'm the friend or worse, one of the best friends of the boyfriend, I started eating her mouth more eagerly than she did mine. We were like 15 minutes eating each other's mouths while massaging that beautiful Booty, trained but soft, then I grabbed her and pushed her against the wall and said let's go to the bathroom, I can't take it anymore before she could respond, I grabbed her hand and took her to the bathroom, luckily it was pretty empty, put her in a vacant stall and sat down on the toilet, there I told her look how you have me, slut and lowered my jeans and boxer showing her all my hard cock, started putting my hand in her thong and she was already really wet, without saying a word she got down and started sucking my cock like a professional, was like that for 10 minutes until I couldn't take it anymore with the excitement, pushed his cock down her throat and came all inside her mouth, she swallowed everything, got up and ate my mouth for a while as she rubbed her pussy. I went out to see if anyone was around, still empty and we left quickly, no one found out anything. We went back on Friday and the boyfriend didn't come either, unless he didn't do it because he was drunk and I'm still hot about that tiny ass being mine...Continue in part two...