When the Lord God looked at how man was created, he said it was not good for a man to be alone, he needs a companion, he needs a partner. Then he said that he's going to make a helper for the man.
Getting married is not just about the not just about union but it's God's plans for life. God himself is the one that initiates marriage. The purpose of God. Baptism is needed.
Our baptism is really near for our salvation, we must be baptized, must be committed, we must obey the command of God, we must believe in him by receiving baptism so it qualifies to be baptized.
We do have to baptize anyone who does not believe in Christ but we must be willing to believe that God is in us. Engagement does not affect how we see baptism. Engagement is different from baptism.
Whether you are baptised or not, whether you are engaged or not, baptism is still necessary.
Because we need to obey the doctrines of God always. Who Jesus Christ has already called us to do Him.