Praise be to Allaah.
It is difficult to say what their reaction will be. Most parents want their children to marry in accordance with their wishes, and in most cases they will have chosen a wife for their son from their own country, whose customs and tradition are closer to those of the society in which they live. The idea of their son marrying a western woman may be very strange for them and difficult to accept, especially if they have heard about the widespread promiscuity in the West and the freedom with which Western women enter into relationships. They may also want their son to be near them, and they may be afraid that if he marries someone overseas they will only see him rarely. They may warn him about the consequences of raising his future children in a non-Islamic environment. On the other hand, they might agree if they hear that their son is going to marry a decent, upright Muslim girl, especially if their son is going to stay on and work in the West after completing his studies, and if they give any weight to their son’s own wishes – which is a matter that differs from family to family.
Whatever the case, you will not lose anything by entering Islam, whether you marry this man or not. If you become Muslim and marry this man, after you both repent from the forbidden relationship, then you will have got what you wanted. If this marriage is not destined for you, then maybe Allaah will send you another good, clean Muslim man whom you can marry and be happy with. The most important thing here is that you understand that striving to please Allaah by following His religion is more important than all other considerations. In any case, we hope that you will become Muslim and that your hopes will be realized in accordance with the laws of Allaah. Thank you for your trust and your question.