I lost my gf in my first threesome

When I thought about my first threesome, I would think of my first girlfriend. We were so good back then. I thought that was forever. We had a threesome hookup with a friend of her. It was a boy. The threesome was not so bad. It was just I felt competitiveness between the boy and me. Later, my girlfriend and I had a big fight over it and she broke up with me. As expected, she went to the boy we had threesome hookup with. I was so foolish back then.