The Lord God said, “It is not good for the man to be alone. I will make a helper suitable for him.”Genesis 2:18
The first thing in creation described by God as 'not good' is Adam being alone. We were not created to be individuals but for relationships. Eve is created as a 'suitable helper' for Adam. She is not the same as him, but complements him - he is better with her than without her.
God has made a suitable helper for me when he created my wife. She is suitable for me, not for someone else, in the same way that somebody else's wife would not be suitable for me. We are not the same person but God has made us to bring out the best in each other.