[jimmytucson]

I can't say this answers your question but I often find that with a significant other, you almost have a "double life": one you share with the rest of the world and one reserved for just him or her.

Never having tried Pair, I can't form an educated opinion but I'm assuming it's sort of like a Google+ circle with a cardinality of 2. Given the behavior I just described, there might be more of a need for "circles" of 2 than just about any other particular number.

Now take your "circle of 2", throw in some cutesy features catering to the nature of that circle, and I can see why their product is useful to a lot of people.

Probably not that useful in parts of Utah, but elsewhere on the globe, sure.