Moving in for the first time with a significant other can lead to petty arguments about all different things that previously seemed immaterial, including miniscule details such as toilet paper style and direction.
There are people who prefer it when the roll is facing 'over,' there are those who prefer it facing 'under' and there are those who really couldn't care less. Apparently one out of five people will get annoyed if the roll is facing the wrong direction so couples should come to an agreement about their toilet paper orientation pronto. I find 'over' to be the most hygienic and presentable method and, apparently, Jay Leno agrees with me.
This infographic gives a brief history of toilet paper and even explains what each toilet paper style says about the person.