They could be cursed gifts for one couple, but non-cursed items for another. For example, if your groom (or lady) are known for having a roving eye (and hands that often follow), the item could do something adverse if they diddle with another (abdominal pain, turn green, have no ummm. drive). A curse for them. Yet for another groom and lady (lets say the kids get mom and dad's wedding rings), the rings could be simply a magic item to show their fidelity with each other.