Just based on what you shared, my opinion, as someone who doesn't know the whole story, is you probably don't have any kinds of grounds to divorce her, not if there isn't something you don't know about or something you haven't shared or something I'm not seeing.
The Bible does not say to divorce your wife because she isn't a Christian. Paul's advice for a man in this situation was to stay together. But if you asked for the separation, are you doing that? Paul also says not to give any offense, either to the Jews, the Gentiles, or the church of God. Offense in this sense means to trip someone up to sin. A husband is supposed to provide his wife with food, clothing, and sex. Separating from her could tempt her to be unfaithful.
I know if your wife isn't serving the Lord, divorcing her and finding someone who will might seem like the natural thing to do. But actually read some of the things Jesus said about divorce and remarriage, for example in Matthew 5 and 19. He who divorces his wife, except it be for fornication, commits adultery, and he that marries her that is divorced commits adultery.
Sometimes the right way to serve the Lord is difficult and involves struggles and suffering. For Jesus, serving God meant the cross. For Paul, it meant enduring beatings. Some Christians have had to put up with an unbelieving spouse. God uses difficulties and trials to mold us into the image of His Son.