Etiquette Snob here…
Although you may be having an Informal, perhaps even Casual Wedding
Technically a Wedding is a FORMAL SERIOUS EVENT in life.
Hence the need for formal types of address
Mr. & Mrs. John Doe = Married
Mr. John Doe & Ms. Jane Doe* = Married
Dr. Susan Smith-Black & Mr. Jack Black = Married
Mr. & Mrs. Albert King & Family = The Household
Ms. Cathry White & Mr. Bob Brown = Living Together / Common Law
Mr. Robert Jones = Single Man
Miss Diane Jackson = Single Woman **
Ms. Roberta Green & Guest = Single Woman who can bring a Guest ***
* A married woman is never Mrs. Jane Doe… that would imply that she is widowed. Ms. Jane Doe is what is appropriate for either Divorced women, or those who want to be known by their first names and not that of their Husbands
** Miss or Ms. is the correct title for Single Women.
As well, if a couple is dating but not living together, then the proper Etiqutte is to send Invites to both their homes individually.
*** If you don’t know the name of the Date they’ll be bringing (ie you have a Bridesmaid who isn’t going steady with anyone… then it is permissible to just address it to them with & Guest. And the & Guest bit means they can literally bring whomever they choose… so a regular Boyfriend or Best Friend, someone they’ve just met invited along for the Wedding, or if they wish their BFF or their mother… WHOMEVER they want to spend the Weekend with… it is not for you to judge).
Hope this helps,
PS… there is all sorts of different permiations of how to address WHOM (Drs, Professors, Judges, Senators etc) IF you need help on this stuff, just ask.