We are truly saddened to hear about the situation you are facing in your marriage, and we are here to pray with you and provide biblical guidance.
Firstly, let's pray together in Jesus Christ. Lord Jesus, we come before your throne of grace and mercy, lifting up this man and his wife to you. We ask that you would work in their hearts, drawing them closer to you and to each other. We pray that you would soften your daughter's heart and rekindle the love that she once had for her husband. We ask that you would give them both a spirit of forgiveness, understanding, and patience as they navigate through this difficult time. God, we believe in your power to restore and redeem. We pray for a miracle in their marriage, that you would give them a fresh start, a new beginning. We ask this in the mighty name of Jesus Christ, our Lord. Amen.
Now, let's look at what the Bible says about marriage and separation. Marriage is a sacred covenant between a man and a woman, designed by God to be a lifelong commitment. But if an unbelieving spouse separates, let there be separation. The brother or the sister is not under bondage in such cases, but God has called us in peace. For how do you know, wife, whether you will save your husband? Or how do you know, husband, whether you will save your wife? (1 Corinthians 7:15-16 WEB).
It's important to note that God hates divorce (Malachi 2:16 WEB), and He desires for marriages to be restored. But at the same time, God does not force anyone to stay in a marriage against their will. Your wife has made a choice, and while it's painful, you must respect her decision. This doesn't mean you can't pray for her, for your marriage, and for God's will to be done.
The best thing for their marriage right now is prayer, fasting, both of them seeking God, and immersing themselves in the Word. God has given this advice in his word. If any of you lacks wisdom, let him ask of God, who gives to all liberally and without reproach, and it will be given to him. But let him ask in faith, without any doubting, for he who doubts is like a wave of the sea driven by the wind and tossed. (James 1:5-6 WEB).
We also encourage you to examine your own heart and life. While you mentioned that you haven't done anything wrong, it's always beneficial to ask God to reveal any areas in your life that may need improvement. This is not to blame you, but to ensure that you are growing and becoming the man that God has called you to be.
Lastly, we want to remind you that God is close to the brokenhearted, and saves those who are crushed in spirit. (Psalm 34:18 WEB). He is with you in this trial, and He will give you the strength and comfort you need to endure it. Keep trusting in Him, keep praying, and keep believing that He can restore your marriage.