Prince William and Catherine Middleton have written their own prayer:

God our Father, we thank you for our families; for the love that we share and for the joy of our marriage.

In the busyness of each day keep our eyes fixed on what is real and important in life and help us to be generous with our time and love and energy.

Strengthened by our union help us to serve and comfort those who suffer. We ask this in the Spirit of Jesus Christ. Amen.