読めなかった英語 no two people would prefer to partner with each other than their current match,

ソース:http://www.economist.com/blogs/freeexchange/2016/03/matchmaker-heaven

The outcome is ‘stable’;no two people would prefer to partner with each other than their current match,otherwise the algorithm would already have paired them.

two peopleというのは全体から選んだ任意の男女二人のこと
partnerは動詞、each etherはtwo peopleの相手方

訳は
どの男女二人を考えても今の相手よりよい相手となるような二人組みは存在しない。