My Mrs has been seeing her boss for sex with my knowledge for several months now. They have shagged most places. His car,the shop where they work together in Rochester,in his London shop,in his house,his garage,his garden and even a graveyard on one occasion! They have never done it in our house though until yesterday afternoon. According to her they had already got themselves worked up in the shop during the afternoon but his wife had turned up at the end of the day and ruined their fun. Leaving his wife at the shop doing paperwork he said he would give my wife a lift home. They planned for a quicky in the car park but there were people everywhere. They stopped off at two other spots nearby but again too many people. Hence they ended up back at our house. We had agreed that our house was out of bounds. I was supposed to be visiting a customer in Gravesend but luckily i had already taken a small order from them over the phone earlier so i had no need to go there. I heard the front door open downstairs and was about to call out or go down when i heard my Mrs giggling and talking. I recognised his voice with hers. I gave it a minute or two then crept downstairs. At the first landing i stopped as the bloody stairs started creaking,i waited then crept further down until i could peer over the edge of the first floor landing. She had her dress and bra pulled down and he was alternating between kissing her neck and sucking at her breasts. I watched him raise her dress upwards and observed she had no knickers on. She parted her thighs and he wasted no time in finger fucking her as they snogged. She must have been soaked as he was quite roughly using several fingers on her. As i watched he unbuckled and undid his trousers then drew them and his pants down to his ankles. His cock sprang free and it was quite a sight. Usually the stuff you read on here will always say,he had an enormous cock,or,it was at least ten inches,hung like a horse,etc,blah blah blah. My cock is about 6/7 inches,quite thick (my cock not me) and has in the past made my lady,2 ex wives and me happy enough. I havent a clue how big his was but i do know it was big and thick with a large round head to it. It hung there in front of her face and she clasped it with both hands and put the end in her mouth. She sucked it for only a minute or two before she moved and knelt on the edge of our sofa and arched her back. He knelt between her cheeks and seemed to be lapping at her pussy. Then he stood and positioned himself behind her. He slid his cock straight up her and judging by the way she shook she was clearly enjoying it. He started sliding in and out of her with long deep strokes. He was using all of it. Slowly,feeling every inch of her. I watched him softly caressing her buttocks. He licked and wet his finger then inserted it in to her arse and began gently fingering her. She has always said no to full anal but enjoys her arse being played with. Her back wasnt as arched as before and whilst she was obviously enjoying him fucking her you could see she was struggling with his size. He held her long blonde hair as he slowly fucked her. The fucking seemed to go on for ages but it was probably no more than five or ten minutes. He didnt speed up,just kept at the same pace. I watched her start to shake and groan then i saw her orgasm,as she came she slumped forwards slightly. He told her quite sternly to sit back which she did and he resumed using her. He loudly asked her where she wanted his cum and she mumbled "Inside me". "Say please,ask me" he said. "Please,please cum in me,i want your cum",she said. "Where?" he asked. "In my belly,cum in me please",she said loudly. He held her cheeks firmly and slid in to her one more time then seemed to grind against her with his cock embedded deep within her. As he emptied himself she ground back against him. He was groaning and gasping. He seemed to be cumming for England,just positioned there behind her pushing against her. He finally finished and slid free. As he moved away from her a large amount of fluid splashed to the floor and he cursed when more fell on his trousers. Obviously a heavy cummer. They both adjusted themselves and sat back on the sofa for a minute then he stood and said he had to go. With a quick kiss that was almost formal he was off back to the shop. I made my way upstairs and made a bit of noise. After about half an hour she came up and i made out i had been up there doing my book work. She told me everything as she always does and eventually i admitted i had watched them together. She apologised for using our house but i forgave her instantly when her fingers traced the outline of my cock pushed against my trousers. Minutes later she sucked on my cock as i fingered her pussy and stroked her breasts. I noticed faint marks on her breasts and thighs where he had sucked and nibbled her. Despite having quickly showered she was still very sticky as i felt inside her. My cock felt very slippery as i fucked her and after i had cum i could see just how red and sore her shaven pussy was. Sadly a threesome is out of the question as neither him or her are at all interested (i have suggested it many times)so i will have to make do with life as it is. She has no interest in a relationship with him,it is purely a sexual thing. I am aware of her submissive side which probably appeals to him as much as it does to me. He can be rough with her at times and has left the odd bruise where he has gripped her hard but she reassures me he would never get out of control. If we are both as happy as we have ever been then i cannot see the problem with it. We have been together for 12 years and our sex life is certainly the best it has ever been. I think as long as ground rules and boundaries are agreed on then its not a bad thing we are doing.