Whenever I read about regret, I try to verify if it fits my definition of regret.

https://medium.com/illumination-curated/the-structure-of-regret-efddfc07158e

I believe regret is (merely) a product of our imagination, that does not include all details of how thing went, if happened differently. But it is not useless, because it embroids into our intuition, as a reminder to learn and change our behavior patterns.