I am not a revengeful person, but it happened, unplanned, and without me doing anything.
I used this answer before, but it answers this question so well.
When I was in 12th grade, I fell for a girl and asked her out several times. Each time she said no. Finally she told me she had a boyfriend and that is why she was turning me down.
I accepted the situation and moved on. Shortly after graduation, she let me know through a friend that she was available. I asked her out, she said yes, we dated all summer long.
It was the first time that I had a girlfriend. I had dated some, but she was the first one I went out with on a regular basis.
In the fall, I started at the local community college, and she started at the university. She kept making excuses why she could not go on a date with me. I presumed she was busy with studies.
I showed up at her house one evening for what I thought was a date. She was not there. Her father said as an apology, that she never broke up with her boyfriend, he had just been away on a summer job. Her father seemed embarrassed.
The worst part was all of her friends that we hung out with all sumer knew what was going on and none of them said anything.
I was so hurt that it was almost two years before I started to date again. I just did not trust girls.
Now the second half of the story.
About four years after the above, I was engaged to a beautiful, wealthy woman. She was a bridesmaid in a wedding that took place in Bevery Hills. Blonde, blue eyed, knockout figure, encased in a long formal gown, and when she got dressed up, she was drop-dead gorgeous. I was her escort for the event.
During the reception, one of the employees for the catering comany kept eyeing me, which made me very uncomfortable as it was obvious I had a date.
After some time the woman came up to me and asked if I was John Roberts. I stated, “Yes, but who are you?”
She got huffy and said, “If that is all I was to you, I am not going to tell you.” She turned to leave.
Something snapped in me. I did not like her attitude, I really had no idea who she was.
I took her by the shoulder, turned her around and said, “Who the hell are you?,” not nice but I was angry.
She identified herself as the girl above. I said, “Oh, hi, goodbye,” and walked away.
Later I found out from one of the other employees that right after she started at the university, she got pregnant and married the boyfriend. It turned out he was a complete jerk, she divorced him and now was a single mother. She dropped out of school, never to get a degree.
I did not plan it, and even though it felt good, I still felt sorry for her.