Well maybe JRRT was thinkimng of those political marriages, yoou know, like Marie Antoinette and Louis XVI.... the extravagant and the stupid.
Oh wait.... that's a poor example. try the intermarriages of AUstria-Hungary. A bit like Melian & THingol. A rich & powerful man's daughter is married to a monarch of some nowhere to increase those things called bonds. Thingol marrying Mel to have/attain wisdom.
Of course Mel & thing have no parents....
