My mother died when I was 18 and as I was an only child and very close to her, my father sent me to stay with close family friends while he sorted things out at home. A couple in their mid-fifties (I'll call them Bert and Rose), they were regarded as almost family, though I had not stayed with them before. It was very comforting to have Rose there, while Bert was a simple but kind guy who didn't say much but would listen to me pour out my sorrow and cheer me up.
The school term was nearly over and I had a fortnight of holidays waiting, although in my present state I was still numb with grief. But it was early summer, and after a few days I began to settle in. I told my father everything was OK and I was being looked after. Dad was very happy to hear that.
One morning after breakfast I was helping Rose with the washing up and looking out through the window at the bright morning sunshine, when I saw Bert pottering around the garden much as he usually did, only this time his penis was poking out of his trousers. He must have noticed, but didn't make any effort to cover up. As I stood there, confused and a bit shocked, I felt Rose's arm around my shoulder and heard her whisper 'Don't worry, hon. He does that when he thinks I'm watching. Probably doesn't even know you're there. He loves me, you know.'
Knowing she was there beside me helped a lot, though I was a bit surprised that Rose continued to stand there and watch without calling out to him. As if guessing what I was thinking, she said 'I know you shouldn't be seeing this.' I told her he seemed harmless, but refused to admit that his sharing the sight of his cock with us was enough to make me touch myself through my pants. Rose seemed to be growing tenser by the moment and I could feel her body stiffen and relax. Though I didn't understand why, it seemed to make my penis stiffer and I hoped I wouldn't come in my pants. The pressure of her arm against me increased and she seemed to be struggling to stand still.
Suddenly, putting both arms around me, Rose hugged me to herself and whispered 'Take your pants off.' When I hesitated, she said it again a little more urgently, followed by 'Please'. As I did what she asked, she helped pull them off and I felt her hands on my buttocks pulling them toward her private parts. She gently cupped and squeezed my penis, stroking it with strong, experienced fingers. As my climax built up, she moved her legs apart and pushed my free hand up under her dress. I felt her wet silk panties, then my fingers slipped up past them into her warm slippery entrance. I hoped Bert wouldn't show himself.
I began bucking helplessly against her hand till I erupted and covered it in warm sticky goo. I heard Rose say 'Oh, my poor darling, you must feel so good now.' Then she applied both hands to herself, making sure I could see what she was doing. I nearly had a second orgasm on the spot.
When we had finished, Rose made me promise never to tell Bert or my Dad what had happened. We cleaned up and put on fresh clothes. That was the start of a special relationship between me and Rose. When Bert wasn't around, she would 'catch' me masturbating, or I'd find her doing the same, and we'd enjoy each other's intimate parts in a way that taught me a great deal about women and helped me in later life.