How can one deal with a forbidden relationship that has been ongoing for four years with a girl who collapses when he tries to leave her, coupled with the fear of bearing the sin of her harming herself?

These widespread relationships between young men and women, under the pretense of love and marriage, are a gateway to evil and corruption. If a heartfelt attachment occurs between a man and a woman who are not mahram (definition) to each other, it is not permissible for them to exchange words or messages. Rather, the legitimate path is for him to propose to her family if he is capable of marriage. If marriage is not feasible, then they must turn away from this attachment, and each of them should strive to maintain their chastity through marriage and occupy their time with what benefits them. One must promptly repent and sever the relationship with this girl, and beware of the snares of Satan, for remaining in the relationship is the sin, not severing it.