I think that in my previous post I was taken too literally : )

All I really wanted (and probably miserably failed) was to bring a couple of examples of minor, insignificant, issues that can become source of tension, sometimes to the extent of destroying relationships.

Change the toilet by toothpaste, the horrible taste in clothes your partner has, or anything else and you can find dozens of examples how such small things has the potential to create so much tension in relationships, that otherwise could have been successful.