Waiting for marriage

First of all I respect waiting. But I don't understand why, what if it's bad, or you don't like it? Sucks for you? I was raised to live with and have sex before I get married or even engaged to make sure it's right since it's the rest of my life. No this does not mean I sleep around, I am with the guy I love and we plan to move in together in May after a year and waited six months to have sex but I can't image waiting until my wedding night and realizing we are not sexually compatible or after living together and married and not living together well. 
I am here for honest thoughts, I am not judging those who wait I am just asking why.