I ended up sleeping with my junior at work... Even though I have a fiancée, I don't understand why I did such a thing. During a drinking party, I originally intended for it to end with just hugging, but I was tempted by the feel of her big tits. I honestly blurted out, "I wanna grope your breasts..." When we were alone, I repeated those words as I groped and licked her breasts. Since we were at the office, I didn't kiss her at all. Later, guilt started to creep in. I decided to stop it, but then we ended up alone together at work again, and she seemed slightly interested. Once more, I made her say "touch me" and groped her. We were at the office, so I couldn't go further. I did it again... It felt like she was into it too, and I regretted getting into such a complicated situation. A week later, we laughed about it. I told her, "I can't date you, and I don't want to hurt Yumichan, so let's not do this again." But Yumichan seemed to want more. Strangely, I ended up saying, "If you can handle this as an adult without regrets, then maybe we could do it again?" In the end, I even gave her a handjob right in the office. This was our third time in two weeks... I gave in to her big tits and my own desires, and I feel pathetic for losing control.