The Jews of Jesus' day had an interesting engagement custom. When a man asked a girl's father permission to marry, and he agreed, then the parents and the couple would meet. The groom-to-be would take a cup of wine, offer it to the girl, and say something like, "With this cup I offer you my life." At that point the girl could refuse the cup, and turn down the proposal of marriage. Or she would take it and drink it, accepting him.
Here is your wedding vow into your union with Jesus.
I believe Jesus has this in mind when He institutes the Eucharist. Part of what's going on here is Jesus inviting us into a relationship with Him as personal as marriage. Salvation in Jesus is as joyful as a wedding. Life in Christ is richly rewarding as a marriage is meant to be.
Jesus is the husband of the church. He leads and provides for us. He loves us tenderly and faithfully. We submit to him gladly. I, Steve, we the church, take You, Lord Jesus to be our wedded bridegroom.