If you are inviting a single man or woman to your wedding, it is not mandatory, but quite polite to invite them to bring a guest. If you know they are in a serious relationship with someone, then you should invite both of them to your wedding.
If you know both of the individuals involved in the relationship, and they live separately, send each of them an invitation addressed specifically to them.
Ms. Sandra Allen 123 Any Street Anywhere, Ohio 12121and
Mr. Timothy Smith 459 Basil Street Somewhere, Ohio 34989If the couple lives together, write their names separately on the same invitation.
Ms. Sandra Allen Mr. Timothy Smith123 Any Street Anywhere, Ohio 12121
If you don’t know the person your guest is dating, send an invitation with their name and guest written on it.
Mr. Timothy Smith and Guest459 Basil Street Somewhere, Ohio 34989
If you receive an invitation that does not include a guest, you should not bring one. No exceptions.