What does knowing the number of lovers of your significant other tell you about them?

I guess not everyone asks this question of their significant other, but I think many of us do, eventually. Why do we ask? What do we hope to hear? How do we interpret it when we hear it?

I guess I’m interested in both your personal experience and interpretation of this, as well as your perception of what the general interpretation of the answers to this question is.

Also, if you want to divulge your number, feel free to do so, but I don’t expect anyone will want to. Which leads to this question: why do we want to hide it? Is it that we don’t trust the public, in general, to understand?