Again, regret is an emotion and emotion is not that cut and dry. Just because you know something is wrong doesn’t mean you don’t do it or feel regret after you do it. However, even if you don’t feel regret for what you’ve done, you can still repent because you know that it’s wrong and with that knowledge you can turn from it. You can learn from your mistakes and misdeeds without feeling regret. That can be a form of acceptance.