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.
It is impermissible for you to marry such a girl if she is as you have described her unless she disassociates herself from all these corrupt beliefs, commits herself to Islam and performs the five daily prayers. If she did so, then it would be permissible for you to marry her.
It is worth mentioning that it is impermissible for a Muslim man to have a love relationship with a woman other than his wife. We wish to warn you against the peril of such a relationship, since it is a path to debauchery and evil.
Allaah Knows best.