My girlfriend persuaded me to have a threesome with her and another man. It was a turn-on at the time but sex hasn’t felt the same to us since. She is 24, I am 29 and we have been together for 5 years. She had only ever had sex with me and said that she was curious to experience intimacy with another man. She said she knew she was not my first but, as she’d never had sex with anyone else, she wanted to even things up. She knew a younger guy of 20 who had told her he had never had sex. This was a real turn-on for her. She talked to him and explained what she had in mind. She arranged for us to meet up in our local pub the following weekend. We all had a few drinks but not too many, then we went back to my flat. I am taller than this guy and I had assumed I would have a bigger penis. The thought of being the bigger and more dominant man turned me on. But I was so wrong. My girlfriend smirked when he dropped his pants and I was shocked. He was far bigger than I am. We had agreed that they would be the main action but that I would stay in the room with them. They started trying different positions. It was embarrassing at first but I then became incredibly aroused seeing another man having sex with my girlfriend. She held my hand all the while but had a much stronger orgasm with him than she does with me. When I have sex with her now, she feels bigger and she has admitted that I feel smaller to her, too. Maybe its all in our heads but me especially believe there is a difference. She has bought a sex toy which is a dildo. It is the same size as he is and she wants me to use it on her. She did tell me, though, that I give her lots of pleasure in other ways, such as kissing, massaging and making her feel loved, which is reassuring. Thing is now she is desperate to repeat the threesome and has invited him over again when things settle down again. I find the thought arousing but I am worried that sex will never be the same between us.