First of all, if he quickly plunges into a new relationship after a breakup, it often hints at his quick forgetfulness of the previous relationship. This seamless behavior, whether it is out of boredom with your feelings or because he has already had a new love, means that his feelings for you are gone. At this point, your redemption will only make him feel more attractive, and your efforts may only be a foil for his new relationship.
Secondly, if he spreads negative remarks about you after the breakup, it shows that he has a grudge against you. This resentment may stem from his own character flaws, or from a huge personality difference between you. In this case, even if you get back together, it will be difficult to eliminate the resentment and revenge in his heart, and it will be difficult for such a relationship to last long.
Also, if he doesn't react to your redemption or even acts more aloof than a stranger, it could mean that he has let go of the relationship completely. He had expectations for you, but the accumulation of disappointment made him choose to let go. At this moment, he is no longer willing to entangle with you, he just wants to look forward. In the face of such an attitude, it will be very difficult to redeem, but if you are really willing to try, you might as well express your heart boldly, at least let yourself have no regrets.
However, if he doesn't exhibit any of the above behaviors after the breakup, then you still have a good chance of redemption. He may still be hesitating, waiting, or expecting your change. As long as you can be honest with each other, solve the underlying problems that led to the breakup, and re-establish trust and love for each other, it is not impossible to get back together.
Redemption after a breakup is not an easy task, it requires not only a change of heart from the other person, but also a healthy and stable relationship between you. But as long as you are truly willing to work hard and are willing to pay and change for the sake of this relationship, then your efforts may not be in vain. After all, love needs both parties to operate and maintain together, and only by paying hard can we reap a happy ending.