You know, we could always say that the ones that DON'T have a pairing never GOT a pairing?
Like, they went to FIND the one they wanna marry, since, say, their nation doesn't really like contacting other people. Because, come on, no nation that has an ounce of power would let another nation marry off their sons and daughters- there is cooperation there. If there is no cooperation, however, then there are no pairings.

So it may be that some people are there looking for a partner.