Are the difficulties faced by the two young people a punishment from God for a sin they committed, and what should they do to repent and return to God, and what is the ruling of Islamic law on their issue?

Allah has forbidden indecency and has forbidden the paths leading to it, such as intermingling and private seclusion with a non-mahram (definition) woman. He has commanded lowering the gaze and warned against following the footsteps of Satan, which cause a servant to fall into indecencies. A servant may be deprived of provision due to the sin that afflicts him. Therefore, whoever has fallen into sin must offer sincere repentance, increase in acts of obedience, regret what has passed, and resolve not to return to it.