I made the mistake of thinking like a guy.... Yes, I should have known better, but you know how it goes, when you grow up as one, you tend to have lapses. 
Guys tend to think in logical formats, Ladies tend to think in abstracts. Not that this is bad, it is different. After over 13 years of marriage, you would think I would remember that.
So the debate has been going on now for those 13 years of where her side of the bed stops, and mine starts. When I heard the term "your side", I of course thought of the logical 50%. I couldn't figure out how being well onto "my side" I still ended up with a bruised shin on occasion.
As a guy, we tend to think of getting out a tape measure, dividing the measurement by 2, and there you have it. My half, and your half.
Uh, no.
I guess it has finally sunk in, My half is the half that is not currently in use. That may be spread out over different sections of the bed, or it may be the bottom half. We may be splitting the bed diagonally as the case may be.
Just thought I would share this as a reminder.