Is it necessary to inform the girl's parents of the details of her actions, or is there another solution, knowing that she no longer responds after attempts to advise her and call her to repentance, and fearing for her from this path to preserve her life, reputation, and honor?

If you love a girl and intend to marry her, invite her to repentance and uprightness, and try to persuade her and her family to agree to a legitimate marriage; for it is the solution for those in love. If she does not repent, then turn away from her, out of concern for your religion and your honor. As for her wrongdoings, advise her gently, and threaten her with informing her guardian if she does not respond, then inform him by hint. Do not spy on her by hacking her accounts, but it is permissible to look at what is apparent and public.