What is the reason for the questioner's constricted chest, is it due to her illicit relationship with a young man, and how can she rid herself of her attachment to him?

A girl's relationship with a foreign man and going out with him is one of the gravest evils forbidden by Islam, due to the sin, destruction of chastity, honor, and life it entails. The young men who engage in this do not desire marriage; rather, they seek amusement, gratification of desires, and to lure girls into indecency, then abandon them. Therefore, this relationship must be severed, and sincere repentance offered. If the person is sincere and desires marriage, let him repent and propose through the legitimate Islamic channels. The distress you feel is the distress of sin and distance from Allah, confirming the words of Allah the Almighty: (And whoever turns away from My remembrance - indeed, he will have a difficult life, and We will gather him on the Day of Resurrection blind). Therefore, one must realize the danger of these actions before regret sets in, seek assistance through supplication, acts of obedience, and righteous companionship, and remember standing before Allah and the consequences of these actions.