What is the ruling on a man and woman who have agreed to marry engaging in phone sex, and what action is required in this situation?

This relationship is forbidden even if it is free of what was mentioned, such as engaging in phone sex. So how about when this abominable act is committed? It is obligatory for both parties to initiate repentance and cut off this forbidden relationship, which is among the ways of Satan. If the man is sincere, let him propose to the woman's guardian for a lawful marriage.