Romeo and Juliet couple

noun2

1. •
   A couple who have married without their parents' consent.
2. •
   By analogy with the two Shakespearean characters, a couple consisting of one member from each of two opposing families, parties, or countries.

   • There are, for example, the Romeo and Juliet couples, who come from warring or enemy nations and escape to a neutral third country […] — 1988