God gave marriage to us and yes, He wants your marriage to last. As Jesus said, "Therefore what God has joined together, let man not separate" (Matthew 19:6).
But this is one reason why God doesn't want you to be involved in this kind of relationship. To put it simply, you would be greatly reducing your chances for a lasting marriage by doing this. You see, a lasting and secure marriage must include two elements: commitment and trust. But this is exactly what will be lacking in this relationship nor will they have much opportunity to grow and develop in it.
My prayer is that you will seek God's will for your life including your future spouse. God made you and He knows all about you. More than that, He loves you and He wants to lead you to the person He has chosen for you. And when He does, you will realize that His way is always best. The Bible says, "As for God, his way is perfect" (Psalm 18:30).
Begin by facing your need of God and then giving your life to Jesus Christ. He wants to forgive you for your sins and then direct your path in the future. Don't be deceived by what sounds to you to be best, but trust Christ to lead you into His perfect way.