There’s the obvious one: you haven’t found the One yet. The not so obvious ones would include any potential emotional hick-ups you may have about being in a relationship (not that you would, not really, it’s always the guys’ fault, isn’t it?) and, of course the reason listed in the below quote. I bet you didn’t think of that one yet. Unless, of course, you found the perfect in-laws and it turned out they had no children…