Princess Stephanie was Maria Henricka's daughter and was married to Crown Prince Rudolf of Austria in 1881. Rudolph died, probably in a murder-sucidie pact with his mistress, at the Habsburg family hunting lodge at Mayerling in 1889. Theoretically, republics should not be perturbed by such romantic mishaps, but Bill Clinton and the Republican Party bitterly opposed to him proved otherwise.
She married Hungarian Count Elemér Lónyay de Nagy-Lónya et Vásáros-Namény in 1917 and died in August 1945 in Pannonhalma Hungary, then under occupation by the Soviet Union while her native Belgium had been twice trashed by Germany and was heading towards NATO membership alongside a re-formed Germany.
Her Wikipedia article is here.