I hate it when people think they have all the answers

I really hate it when people act like they have all the answers when it comes to relationships.

My SIL (sister in law) has never been married, never even lived with a guy, yet she seems to have all the answers to what I am doing wrong in MY marriage.

Worse yet, my husband has a friend who is in the middle of a nasty divorce, and he, too, gives us unsolicited advice.