There are people who claim they have no regrets whatsoever. They'll tell you something like "if I had to live my life again I'll make the same mistakes, take the same decisions, change nothing".
Well, I belong to the opposite category. I do have regrets on things done / said, or on things not done at all (inaction). I usually blame myself ( ignorance, naivety, trust in the wrong people) for the matters regretted.
There's a famous song , originally performed by the french singer Edith Piaf (rip) , named "Non, Je ne regrette rien" (No, I regret nothing). According to this song, things that went wrong, make us strong. Grief doesn't last, it's a matter of the past.
True. Even if we regret our choice, some good might come out of it. We can't change the past. We can, however, try to focus on the present and the future. We can learn to apologize. Apologies give us peace of mind and sometimes save relations.
Still, I have regrets regarding many topics in my life, among them:
Staying in touch with friends from childhood and youth; Romance (breaking ups, getting dumped, dumping someone); Career and Jobs; Family ties. The only consolation is the thought that with any choice made there would probaby be positive as well as negative aspects to deal with.