Dogging my girlfriend

It was a late October night and my girlfriend and I were board. I suggested we went out and have a couple of drinks so we did. Later after a couple of Drinks I suggested we go out dogging again. We had done this a few times before my girlfrien who was a size 10 blonde, small petite tits with a nice trim pussy agreed to go. She was 30 and I was a fat 36 year old who loved to masterbate while watching her fuck strangers.
First she decided to get dressed for the occasion no bra a see through black top, a very thin black thong, black knee high leather boots and finally a PVC mini skirt and she was fit and ready. I just wore a baggy tracksuit for easy access.
We drove down by the river our local spot. We had many a good night here before. By now we were both hot excited and I would be encouraging her to enjoy it all the way there.
As we parked up, no other cars about she removed her thong and put it on the gear knob. We kissed for a while waiting with excitement for someone to arrive. A few minuetes pasted and a car parked nearby about 3 car spaces away. It was dark and there was no lighting but this only added to the excitement. By now I was hard and could not wait to see her fucked again. I said are you ready then and she replied yes, as she did she hitch up her skirt and started playing with herself. While I watched and waited.
Suddenly we both heard a door close here he comes I said, both of us not sure who it would be old or youg fit or fat etc.
Then a face appeared at her window an older man about late 50's early 60's looking at my girlfriend playing with herself. He was already wamking outside the car. My girlfriend turned and looked at him as I put her window down on the switch. Alright I said. Hello very nice he replied. Would you like a feel. Oh yes he said and with that he put his arm in through the open window after wetting his had in his mouth. Then gently at first started rubbing her clit as she moaned with pleasure, soon they were both kissing and his hands were all over her! I was so hard wanking away, this was heaven for all of us.
I could see more of him now he had a very full beard and I was slightly surprised how old he was and how much she was enjoying him. Time for me to get it moving on I thought. So I said to him do you want to fuck her then? Oh god yes if it's ok with you he quickly replied looking at my girlfriend for a reply.
With that he moved away from the car she nodded and said fuck me on the back seat,
In the back they got she lay down with one leg on the back shelf and the other on the floor. He wasted no time slipping his big stiff old cock.in her god this was great they started fucking, kissing and touching each other like sex starved maniacs it was so hot to see I was going to explode.
This was the first time that she had been with a stranger this old and she was enjoying her experiance more than ever.
I had never left her with a stranger but I had always wanted to, as I thought of how exciting it would be for her to tell me about it when we got home. So I asked her while they were still going at it would you like me to go for a walk and give you both some time alone. God yes she said with no hesitation. Wow oh shit I thought no going back now, although slightly concerned for her but so excited more than I have ever been I got out of the car and started walking away, I got about 300 yards away and I could see the car moving and wanked myself as I imagined how much she was enjoying his cock alone with him.
Then after about 5 minuetes I suddenly heard her scream a scream that just kept repeating and I shuddered was this a sign? Was she in trouble? What should I do now. Worried for her I went back to the car. I open her door at the back she was still screaming I said are you ok? YES she stared at me as she was now on her hands and knees on the back seat with her skirt folded onto her back. The stranger fucking her doggy style was too busy and at the point of no return to care about my interruption. Then with a good old arrrhhhhh he shot his load inside her, then quickly pulled out, and sat on the back seat. My girlfriend got up and sat with him as I still watch from outside. Thank you he said. No thank you she replied. They kissed and he said goodbye and left.
We both got into the front of the car and I started driving home, in silence for a moment. It was bugging me I was still horny as hell and wanted her bad but why was she sceaming? So I asked her because she said that was the best sex I have ever had and I came four times. Bloody hell I thought better than me ? I asked yes she said. Although I was gutted a bit it also turned me on beyond belief that she had enjoyed fucking him that much.
We got home and as always we both went straight to the bedroom where I told her to think of him as I licked her out as I always did after she fucked someone. The smell of the person still on her there juices together was such a turn on. But soon I could resist no longer I had to fuck her now as I got in her I asked her one last question, would you like to spend awhile night alone in his house with him? Yes I have to say I would love to she said. With that I fucked her hard until we both came.
God that was the best sex we have ever had I said, yes it was earlier she replied.
We both slept and all I could think of all night was how good he had fucked her and how much she enjoyed it.