What is your advice to a shy person who cannot confront their relatives about the sins they commit, and fears that a tribulation may befall them because of these sins, knowing that it is impossible for them to discuss the matter with their relatives directly?

What your relatives are doing, such as harassment and other acts, is a reprehensible sin. You must denounce the evil and advise them, and rid yourself of the blameworthy shyness that makes you silent about the truth. The belief that whoever commits fornication will inevitably have one of their female mahrams be fornicated with has no proof, and the hadith "Whoever commits fornication will have it committed against them, even if within the walls of their house" is fabricated. The meaning of "this is a sound religion" is that the perpetrator bears the sin of their act and will be recompensed for it on the Day of Judgment, and Allah does not hold anyone accountable for another's transgression.