This happened when I was in the sixth form (in the US I think that is senior high?). I started going out with a girl called Marie. She was very pretty - her most striking feature was her long straight red hair. She had what now days we would call a chubby body. As we got to know each other better and started kissing and petting she would eventually let me put my hands on her breasts. One day she let me go further and during a particularly long 'snogging' session she breathily whispered that the clasp to her bra was behind her back. Of course, I knew this but I didn't need to be encouraged any more to unsnap it - my first! - and push it up over her young, full breasts. Of course, I'd seen breast in girly magazines but never literally in the flesh before. They were very beautiful. They were heavy and full, with lovely well-defined areolas and beautiful pale pink nipples. Of course, I spent the rest of the afternoon kissing her and stroking her breasts. We were so inexperienced that I guess it never occurred to either of us to have an orgasm. The next weekend we planned on going to a party together and I met her at her parents’ house beforehand. Her parents had gone out for the evening and when I arrived Marie was not yet dressed. I hung around downstairs while she went upstairs - a bit like a dork, really! - but after a few minutes I heard her calling for me. She asked me to come upstairs. Shyly, she looked at me and asked if I wanted to see her get dressed. I was still quite inexperienced with girls so I sort of nodded and gulped a yes and she turned into what was obviously her bedroom and I followed. She'd been wearing a denim skirt and top. I sat on her bed (the only place) and she unzipped the front of her skirt and it dropped to the ground. She was wearing pink and white striped panties and white socks. Of course, I could not take my eyes from the triangle at the top of her legs where her obviously plush mound made a soft outline. She took off her top and turned her back to me and asked me to unclip her bra, which of course without hesitation I did. She shucked it down and it fell to the floor. Then she turned around to me. I'd seen her tits before but never so blatantly and without her blouse interfering with the view. I admired again how they were lovely and rounded - nicely plump – they looked like ripe globes - I even noticed they had little reddish hairs in places which was very attractive in its way. Marie took my hand and we walked over the bed. She lay down and pulled me to her and we started kissing. Almost immediately it was very breathy and frantic. She told me she wanted to feel her breasts against my bare chest so I unbuttoned my shirt and she helped me get it off. What a feeling! Her warm fleshy mounds rubbing up and down on my bare chest. It was like heaven. We kissed some more. Slowly my hands roved over her back and each time they went a little bit lower until not meeting any resistance they delved into her panties and I stroked her bum cheeks. As she didn't object I began to move her panties down as I roved more ambitiously. Again, she did not object and in a few minutes her panties were well down her thighs. Please, she asked me, please can I see your penis? I'd already lost my trousers and in those days I wore blue (can you believe it) Y-fronts with that white piping around them. I was a bit shy and embarrassed. Obviously, kissing an almost fully naked girl had taken its toll and I had a very stiff hard-on in my pants. Which was silly looking back because it obviously was very apparent. Still, she coaxed me a bit - take off your underpants - and I shyly pulled them down and then sat down beside her on the bed. She looked at my throbbing member asked almost reverently if she could touch it. I gulped what was probably a rather high-pitched assent and her hand reached down and gently, carefully wrapped itself around my shaft. I gulped. I had masturbated the day before but I was young, dumb and full of cum. So, I was a bit worried I might suddenly shoot my wad. I was concerned if I did that - in those days a magnificent sight as I could probably blast a target at 100 metres with my ejaculation – without warning it might actually scare her. To get a better grip she stood up and I had to go with her. Ambitiously I put my hand down and touched her mound and began to gently rub it. She absolutely loved it and moaned and gripped me harder. With the luck of a beginner I found the entrance to her vagina and my finger slid in which only increased the excitement Marie was obviously feeling. She let go of my cock and put her hand around my neck and pulled me closer to her. At the same time, she trapped my cock on her mound and started to gyrate against it. Maybe she was more experience than me, I don’t know but she had a technique I’ve never come across since, which is a shame, of grinding her mound quite shamelessly across my cock in an almost circular motion. I had come to the point of no return, “Marie”, I warned her, “I’m going to cum! I’m going to shoot my load!” Again, my chief concern was not scaring her with the mess this would make but my entreaty only made her rub me even harder as she breathily said, “Can I help?”. She hugged me harder and as I began to cum she was breathing and sighing very loudly and shaking as well. I pumped and pumped – for a brief instant I even wished I would hurry up and stop pumping away! – and I could feel the area between us getting very wet and sticky but still Marie hugged me and was almost sobbing with excitement. We stood clinging to each other for what seemed like a long time. I was overcome with that warm, contented glow from a very satisfying orgasm, which fortunately I have experienced many times since in my life. I like to think looking back that with the luck of beginners she had also had an orgasm, as well – it certainly sounded like it. Eventually, as my young manhood shrivelled to a normal size, Marie disengaged from me and picking up her panties went into the bathroom. I sat on the bed and with some nearby tissues mopped myself up and put back on my underpants. Eventually, Marie returned and lightly kissed me on the lips. She asked me to help her get dressed, so I found her bra and helped hook it up and then retrieved my shirt. I don’t remember much more of that evening – I think we did go to the party – and in fact, only a few days later we had a childish tiff and Marie ‘chucked me’ and ended our relationship. Then my parents moved away and I with them. We did write to each other a few times and one time I tried to get her to come and visit me – knowing full well that the weekend I chose was when my parents would be away but she never did. We didn’t fuck that night but it is still one of the best sexual experiences I ever had.