The infograph says it all. This is likely skewed more towards the younger (high school and college) crowd – as evident of the higher numbers around spring break. Maybe people want to be single when they go away for the week so they break up beforehand. But more likely they “got in trouble” while apart from their significant other.
Oh, and look at the spike right before Christmas time. Other than cheating, nothing seems to motivate people more to finally break up than having to buy a present for someone they don’t really care about anymore.