You are who you are and did what you did or didn't. For the most part, regrets are best left for future decisions. Like not getting those handmade shoes when you had the chance. But one regret in particular springs to mind.
It was my first job fitting a kitchen. I did not drive at the time, so I took the train plus bicycle 15 miles. The sparks had taken nearly all day doing his job and the sink needed to be fitted. Like I said it was my first so it took a while. and by the time I finished the last train had gone. Meanwhile, the woman who was there was drinking with her friend and the guy was gone for the night. She asked me to stay, whilst stroking the shaft of my hammer in a very provocative manner. I phoned my wife to let her know about the train etc. and she pleaded with me to come home on the bike and put the kids to bed.
So a definite bit of extramarital sex and quite possibly a threesome or a 15-mile bike ride? Like a schmuck, I caved and rode home.
A Solzhenitsyn quote goes "There are jokers in this world that run round in circles for fun. Let them try it after a hard day's physical graft". The ride home took forever. What was a journey that I had often ridden on nice summer days became excruciatingly painful. "But I had done the right thing," I thought. Till she filed for divorce 6 months later and the kids could get to bed without me.
I had passed on the only chance of a threesome I am ever likely to get for some misguided sense of loyalty. Yet we are what we are and do what we do so our regrets make up parts of us just like everything else.