While the tweet was obviously intended to celebrate both same and opposite-sex relationships, it seems many were not impressed with the airline's message.
One Twitter user remarked that according to KLM, "your only chance of surviving a crash is buckling up the heterosexual way".
And another responded with: "I see only gender binary represented here". While another pointed out that "actually it does matter who you 'click' with, some don't match up for a reason, stop trying to force your agenda down people's throats".
Despite the online hate, the post still got more than 5,000 likes and more than 3,000 comments, which just goes to show, even bad publicity is good publicity.