Wedding Tips: Partners, Fiances, and Boyfriends - Who to invite?

Partners, boyfriends, fiances...who gets an invitation?

So you are trying to manage your guest list and wondering if you can leave out Mary's boyfriend. After all you don't know him very well. Is it rude or just good wedding business? The rule of thumb is to invite the partner of anyone who is married, engaged, living with someone, or in a relationship of six months or more.