Is it permissible to supplicate, give charity, perform Umrah, and visit the grave on behalf of a girl who died after an electronic relationship, and is it permissible to supplicate that the deceased and the questioner be gathered in Paradise?

One should not resolve to never marry, as this goes against the practice of the Messengers. Repentance from the feeling of guilt—that you came between the girl and repentance—is sufficient, and it is permissible to dedicate the reward of good deeds to her. Visiting her grave for reflection and supplication is permissible, and you bear no sin for advising her to undergo the operation, for death is in Allah's hands. As for supplicating that she be your wife in Paradise, its benefit and responsiveness are unknown; rather, your concern should be entering Paradise itself.