as salamu alaykum dear sister,

You stated you were in a relationship with this boy for 5 years.  I do not know what you mean by relationship, only you do and you know that in Islam we do not have boyfriends.  With that said, I will leave that part of the issue between you and Allah.  Regarding this boy and how he comes from a religious family, apparently, he is not that religious as he is committing zina, living with a woman and has cheated several times on you.  It seems to me sister, he has issues.  First of all, he can’t keep his promise to you to be chaste.  He cheats, he lies and worse-he disobeys Allah and commits sins.  Do you want to have a possible marriage with someone like that?  Don’t you feel you deserve someone who is pious, fears Allah and will be a faithful, trusted a husband who will guide you (and any future children) Islamically?  I feel you deserve better.

As far as him making istakharra about who to marry-you or a non-Muslim woman, as he is commiting zina and disobeying Allah I am not sure if Allah will answer his prayer.  Additionally, while you may feel you are a better choice, only Allah knows. This non-Muslim woman has not taken shahadda, she is not yet responded to Allah by an oath. Perhaps she does not even see the errors of her ways. Perhaps, Allah may use this boy to lead her to Islam and she may become a wonderful Muslim, who knows? We cannot say we are the better choice sister, only Allah knows.  However what ever the choice or case may be, if she does end up with him and becomes a practicing Muslim, surely she would deserve better than him.

While it is good to make duaa for our brothers and sisters who have fallen short or are in need of spiritual guidence, please do not do so with the intention of marrrying him sister, if you make duaa do so for the sake of Allah to assist one who has fallen short.  Remember also that while we can make duaa for others, it is up to that individual to want to change and repair their relationship with Allah.  Allah will change the condition of a people if they change the condition of themmselves.  In this case, it would mean that this boy stops his haram lifestyle, sincerely repent to Allah for his sins and stay on the right path.  This is something you cannot chage, it is between him and Allah swt.

I would kindly suggest dear sister that you move on with your life, forget this boy (yes you will  need time as you knew him 5 years)  and try to insha’Allah focus on things that are more spiritually upbuilding for you and your life, which of course includes getting closer to Allah swt and trusting in Him with your heart, life plans as well as any future marriage. We wish you the best you are in our prayers.