I have been with my girlfriend, Lucy, for five years now. I am 28 and she is 23. She is a 5’6” tall brunette, size 12, with very pert 36D breasts. Whenever she goes out on the town she always wears the smallest of dresses that accentuate her natural curves and, whilst this turns me on when I’m out with her, I naturally worry what sort of attention she’s getting when she’s out with the girls. Anyway, a few years ago, when we first got together, I was very quickly initiated into the world of sharing my girlfriend. She was eighteen at the time and we had been invited to a house party in the summer. She made a very special effort to get ready and looks simply amazing with a very tight, short, dark blue dress. She shaved her pussy for the evening and wore bright red lipstick – something I hadn’t seen her do before! I also knew that she had no bra or knickers on because, she said, they would show through the clingy material – explanation accepted. Moving on, we arrived at the party and it was all of her friends, girls and boys whom she knew from school and college mainly, and a few older ones she knew from the town scene. She had an awful lot to drink and she kept leaving me to chat to people she had introduced me to. Now, I was 23 so I wasn’t out of place or anything; I just didn’t really know anyone! Very late in the evening, certainly gone midnight, I was chatting to one of Lucy’s friends, Sally. Sally was being very chatty and asking me about work and my family and things like that. After a while, I thought I’d go and find Lucy, but Sally was very obviously trying to hold me back and distract me. Sensing something was wrong, I explored the house and, amongst all the drunken kissing and groping all over the house, I went upstairs to find a bedroom door being sort of guarded. I pushed past and a small crowd of lads were watching couple on the bed. Some lads were wanking, other just cheering, and a few were filming it on their mobile phones. My heart sank as I realised that one of the girls was Lucy, writhing around naked on the bed with Dean, a black lad she used to go out with when she was fifteen. Also on the bed was one of her good friends, Kate, who was busy fucking her own ex next to them. I watched in disbelief as Lucy sucked Dean and I felt sure that, whilst she was far beyond the boundaries of acceptable, that she would not actually fuck him. How wrong I was; he lay down on the bed and she straddled him, guiding his admittedly large dick into her pussy. Lucy gets very wet when she’s turned on and he really seemed to know how to get her going. His dick was far bigger than mine and, whilst we had a good sex life, he was fucking her so good, like an absolute whore. I shouted out to her to stop, and she looks petrified when she saw me. I left the room shaking and I marched outside onto the street. She soon ran out after me and we had an almighty argument in the street. We went for a walk to calm down a bit and we sat down in the local park. She told me that she loved sex with Dean and that a party trick of hers and Kate’s was to fuck Dean and the other lad at every house party they went to; it was almost expected! Dean had had loads of girls and was a bit of a local stallion, and it was a show they had been putting on for years for the other party goers. She said it had all started when, as young lovers with nowhere to go to have sex, they would go to Kates and all four of them would fuck on the same bed, often changing partners or becoming one big foursome. Lucy and Dean had finished but met up at a party when they were still at school. He told her he wanted to fuck her and, with drink and god knows what else inside her, she agreed to let him. He told his mates and it soon became a performance for a trusted few to watch. Lucy is the sort of girl lads aspire to fuck and, with her lovely tits and shaved pussy, notwithstanding her fantastic fucking ability, she was easily going to be Dean's choice for a drunken teen fuck fest During this conversation, the anger dissipated and I began to reconcile the events in my head. I had made up my mind that we were finished, but I wanted to fuck her one last time, and there, in the park. We kissed and I fingered her soaking wet pussy – I think I could have got my fist up her! And then she released my cock from my trousers, sucked my a little, and then straddled me on the park bench. I ended up fucking her in lots of positions and calling her all the names you would expect: whore, slag, slut, dirty bitch, and she just got off on it! We went back to mine and fucked each other all night. She told me of more escapades with Kate and even showed me videos of previous times she’d been filmed with Dean. We worked things out, but I had to accept that she would continue to put on a show at the parties. She said she loved the thought of other dicks wanking over her and had, on occasions, invited others to join in. We agreed that I would never watch, or join in, but that I could go along to the parties and stay downstairs. We had to wait until New Years Eve for the next one, and I was very apprehensive about what was to happen. Again, she looked fantastic when she dressed up and I knew it was for somebody else to fuck her. It was a strange feeling being at the party and knowing that everyone knew my missus was going to be fucked by someone else later on the evening, and I kept feeling jeaous, but at the same time turned on by what she was doing. Afterwards, she took me off to a quiet bedroom and let me fuck her used pussy. She also made me taste Dean and the other lads cocks that had been inside her mouth, and I must admit to finding it a huge turn on. Five years later, and maybe another ten or so parties, and we’re still together. I know she’s not wife material, and she swears that Dean (and others at those parties) is the only time she is unfaithful to me. Whilst ever she still loves his cock, and he loves her tits, I'm going to have to put up with it.