Once you start living with your SO, things start to change. After a certain amount of time, (like, a year and up) manners and habits you previously disregarded or straight up ignored can start gnawing away at you. There is no perfect, problem-free relationship, just as there are no perfect people. Some pet peeves are worse than others, though. They range from kind of gross to inconsiderate to downright blasphemous (see: 13 and 16).