Why this photo of political spouses and partners is making waves

(CNN)What's the first thing you noticed about this picture of political spouses and partners, other than Melania Trump's continued mastery of the color black?

It's probably the man in the back row, standing out against the nine women pictured. That's Gauthier Destenay, the First Gentleman of Luxembourg and the husband of the world's only acting openly gay prime minister.
Destenay and Luxembourg Prime Minister Xavier Bettel wed in 2015, right after Luxembourg legalized gay marriage. When Bettel won the Prime Ministership in 2013, he was already in a civil partnership with Destenay and their sexualities were not a secret.
To be clear, Bettel isn't the only gay prime minister ever, just the only one in office right now. Former Belgian Prime Minister Elio Di Rupo and former Icelandic Prime Minister Jóhanna Sigurõardóttir were both public about their sexualities.
    Can you name the rest of the people in this photograph? We'll help you out:
    First row: First Lady of France Brigitte Macron, First Lady of Turkey Emine Gulbaran Erdogan, First Lady of the US Melania Trump, Queen Mathilde of Belgium, Secretary General of NATO Jens Stoltenberg's partner Ingrid Schulerud, Partner of Bulgaria's President Desislava Radeva, partner of Belgium's Prime Minister Amelie Derbaudrenghien
    Second row: First Gentleman of Luxembourg Gauthier Destenay, partner of Slovenia's Prime Minister Mojca Stropnik, and First Lady of Iceland Thora Margret Baldvinsdottir.