Will the advisor to those in an illicit relationship, who is accused of hypocrisy in his advice, be a cause for the other party's suicide if it occurs? Will his deeds be invalidated, and will he be held responsible for what befalls the girl? And is it permissible for him to supplicate for repentance from hypocrisy?

You have done well in advising the young man and woman regarding the relationship that is not permissible in Islam. Do not pay attention to the thoughts that you might be the cause of her suicide; there is no sin upon you if she commits suicide, for she is the one who transgresses against herself. Allah says: "Every soul, for what it has earned, is retained," and "Whoever is guided, he is only guided for [the benefit of] his soul. And whoever errs, he only errs against it. And no bearer of burdens will bear the burden of another." Her acknowledgment and appreciation of your advice confirm that you are not the cause of that. As for showing off (riyaa'), the default is that you did not do that out of riyaa', for certainty is not removed by doubt.