My view of relationships and marriage is this: when the couple is going out, they are merely involved; when they become engaged, they are involved more deeply; but when they publicly exchange marriage vows, that is commitment. The meaning of the marriage ceremony is the commitment.
To drive home the meaning in a way people usually remember for the rest of their lives, when I preside over a ceremony, I explain the difference between involvement and commitment is the same as the difference between bacon and eggs. At this point, the family and friends start to pay attention. They begin to wonder, "What has bacon and eggs got to do with marriage?" I continue: "With bacon and eggs, the chicken is only involved, but the pig is committed. Let this be a pig marriage."
Mark