No ceremony is complete without the kiss. In fact, there was a time when an engagement would be null and void without one. Dating back from early Roman times, the kiss represented a legal bond that sealed all contracts.
The kiss that seals the wedding is much more than a sign of affection. It has long been a token of bonding -- the exchange of spirits as each partner sends a part of the self into the new spouse's soul, there to abide ever after.
You may now seal your vows with a kiss.
You may now kiss the bride.
You may now kiss the groom.