One can also construct the curse like this:
Willem III of the Netherlands and Queen Sophie of Württemberg were both half Romanovs, on the side of their mothers, who were sisters. Their children seemed cursed and all died young and unmarried, something which extinguished the male line of the House of Orange-Nassau. Queen Victoria in the end refused to help the House of Orange-Nassau rejuvenate itself through the planned marriage between Alice and Willem, Prince of Orange, because Sophie's buddy Napoléon III, fearful of a Dutch-British alliance, had set a trap for him with a Parisian cocotte when he was passing through on his way to Britain. When QV instead married Alice to Ludwig of Hesse, the curse was lifted from the Dutch RF and instead fell upon the family of QV's innocent daughter. Fate's way of telling QV not to be so haughty and holier-than-thou?