The White House omitted to mention the husband of Luxembourg’s Prime Minister in an official portrait’s caption.
Nato leaders’ partners posed together on Thursday to celebrate the group’s meeting.
Gauthier Destenay stood behind Melania Trump and Turkey’s autocratic leader’s wife, Emine Erdogan.
But when the White House shared the picture the caption ignored Mr Destenay’s existance.
Yet to add insult to injury the caption made two mentions of Mrs Trump.
The tiny European nation saw their Prime Minister marry after Luxembourg legalised same-sex marriage.
Xavier Bettel, 44, has run the French-speaking nation since 2013.
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Initially the White House caption read: ‘First Lady Melania Trump poses with Belgium’s Queen Mathilde, center, and other spouses of Nato leaders: First Lady Emine Erdoğan of Turkey; Iceland’s Thora Margret Baldvinsdottir; the First Lady of France Brigitte Trogneux; First Lady Melania Trump; Slovenia’s Mojca Stropnik; Bulgaria’s Desislava Radeva; Belgium’s Amélie Derbaudrenghien, and Norway’s Ingrid Schulerud, during their visit Thursday 25 May 2917 [sic], at the Royal Palace in Brussels.