Is it permissible to hold a friend responsible for disagreements between two lovers, based on his joking with one of them and his knowledge of the details of their relationship?

You have erred by engaging in an illicit relationship with a girl outside the bounds of marriage, and you must repent to Allah and cease these relationships. If you wish to marry, let it be in a lawful manner by proposing to the woman through her guardian if she is pleasing in her faith and character.