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.
First of all, we advise you to continue supplicating Allaah, as the best means for achieving one’s objective is supplicating. Indeed Allaah ordered us to supplicate Him and He promised us to answer our supplication. Allaah Says (what means): {And your Lord says, Call upon Me; I will respond to you.” Indeed, those who disdain My Worship will enter Hell [rendered] contemptible.}[Quran 40:60]
Among the best supplications is the Istikhaarah supplication which is clarified in Fatwa 81434.
Indeed, you did well by being keen on marrying a pious religious woman, and this is what the Prophet urged us to do; for more benefit about the criteria of choosing a wife, please refer to Fatwa 85573.
Based on this, if this girl is religious and Allaah facilitated your marriage with her, then all the best, otherwise, you should look for another woman to marry and do not be attached to her. You should not waste part of your life running after her [and thinking about her] as a person’s life span is limited.
You may seek the help of trustworthy people from among your friends and relatives in looking for a pious wife. Meanwhile, you must cut any relationship with the girl whom you mentioned in the question as she is a non-Mahram to you.
Allaah Knows best.