Couldn't wait to post this! We have my girlfriend's ex-husbands father (Tom) staying for a while so that he can see his granddaughter. His wife died recently and he was a bit emotional and upset on New Years Eve (lack of sleep, too much booze) and my GF was giving him a bit of a hug to comfort him (she still gets on well with him, if not his son). I suggested that as it was so late we should go to bed and GF told me to go up and that they would follow shortly. I went up and got in bed but after a while with no sign of GF, I went back downstairs and into the kitchen, where I could see them through the partly opened dining-room door. Jill, my GF was standing up with her back to me was hugging Tom but he had her skirt right up and was fondling her stocking tops and french knickers, which she didn't seem to be objecting too. I crept up to the door and I could hear him talking about his wife and how much he was missing sex and I was stunned when Jill moved her hand down and started rubbing his cock and saying does this help? I was shaking and had no idea what to do, Jill is always shy when talking about sex with me. She then to my amazement went down on her knees and took out his cock, which was massive by comparison to me, and I heard her saying "I didn't think I'd miss this but I do" and proceeded to give him a hell of a blow job and swallowed, which she has never done for me. During all this Tom was telling her what a good slut she was. When she had finished he took her into his arms and he started asking what I was like in bed, frankly I was staggered when she started telling him chapter and verse. She said that I was good at O, and was very tender with her, but that I only made love very gently. She also told him that I wear lingerie and not just in bed, that to me was getting a bit personal. Tom then said to her, while I am here I am going to fuck you Jill, you know that you need me to do that don't you, she softly just said yes and then he asked what she was doing with a faggot like me and said that his son was a real idiot losing a woman like her because he didn't know the difference between dominance and violence. Well, I knew her ex had been violent and that is why she had left him, and that her father had been domineering as well and she had told me that one of the reasons she wanted to be with me, was that she felt a guy in panties, stockings and a camisole was probably enough in touch with his feminine side to never be violent towards her. She went on to explain this to Tom, adding that I had taught her a lot about loving and she liked that and she thought that she could do without rough hard sex. She told him that she really loved me and wanted to get married (only good news of the new year for me so far) but went on to say that when she had felt his cock against her she knew what she was missing. Tom then said to her, I will fuck you when I am here and either we do it when the wimp is out but I'd rather he watched and saw what you really need, then he went on to add, perhaps if you have him dressed up he can suck me until I am ready for you. At this stage Jill, moaned gently and started kissing him passionately, I crept back up stairs and went to bed, it was about an hour before she appeared and kissed me goodnight as she got into bed. I could taste cum on her lips and she kept her panties on under her nightie, which she rarely does, so I suspect she had been fucked. I was away last night working but god knows what will happen tonight. And I am afraid, seeing my lovely GF giving someone else head has left me with really mixed emotions, why didn't I barge in? Probably because I was turned on, possibly because the idea of being cuckolded has left me with emotions all over the place.