All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
The greatest blessing from Allaah to a person is that He blesses him with insight and a good mind by which he perceives the truth and realizes what leads to his happiness in this worldly life and the Hereafter. Hence, he becomes determined to tread the Path of Allaah, abide by His commands and do what he is determined to do and stays steadfast on the straight Path.
There is no doubt that Islam is the true religion by which Allaah abrogated all previous religions, and it is the religion of all the Prophets. It is the final religion and Allaah does not accept any other religion than Islam. For evidence that Islam is the true religion, please refer to Fataawa 173389, 111063, 88906 and 86091.
You can also benefit from Shaykh Ahmed Deedat's books, which are very good books where you can find strong responses to atheists. We ask Allaah to guide you.
Our advice to you is to hasten to embrace Islam. As regards that man, if he embraces Islam, then all the best. Otherwise just forget him and leave him and be keen on keeping company with righteous Muslim women who would help and support you. Contact Islamic Centers to help you, especially in searching for a pious Muslim husband. It is Allaah Who will facilitate for you embracing Islam and it is He Who will facilitate for you the means of sustenance. Allaah is the Creator and the human being is created; Allaah is the Provider of sustenance and the human being receives that sustenance.
As regards Zina (fornication), it is evil and an abominable deed, and it is a cause for many harms and diseases. It is for this reason that it is forbidden in all religions; rational people from among all religions and persuasions avoid it. Taking a boyfriend/girlfriend is the easiest way that leads to Zina. Hence, taking a boyfriend/girlfriend is also prohibited.
Allaah Knows best.