Alaska Airlines is investigating a claim that a gay couple was separated so a straight couple could sit together.

David Cooley was flying from New York’s JFK Airport to Los Angeles International Airport when he said an Alaska Airlines flight attendant gave “preferential treatment to a straight couple.”

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“I have never been so discriminated against while traveling before,” Cooley wrote on Twitter. “After my traveling companion and I had been seated in our assigned seats for a while, we were approached by the flight attendant and my companion was asked to move from his premium seat to coach, so a couple could sit together. I explained that we were a couple and wanted to sit together. He was given a choice to either give up the premium seat and move to coach or get off the plane. We could not bear the feeling of humiliation for an entire cross-country flight and left the plane. I cannot believe that an airline in this day and age would give a straight couple preferential treatment over a gay couple and go so far as to ask us to leave.”

Cooley said he and his partner managed to get a flight home on a Delta Air Lines and advised others in the LGBT community to avoid Alaska Airlines.

“We will never be flying Alaska Airlines or their recently purchased Virgin Airlines Group ever again. Thank you to Delta Air Lines for getting us home safe. If you are an #LGBT person, please spend your travel dollars with an LGBT-friendly airline like Delta.”

Several have taken to Twitter to share their outrage over the treatment.

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Alaska Airlines confirmed to Fox News that the couple had been moved from Premium Class to the main cabin, but said it was because of a seating mistake.

“When boarding flight 1407 from JFK to LAX, a couple was mistakenly assigned the same seats as another couple in Premium Class. We reseated one of the guests from Premium class in the main cabin. We are deeply sorry for the situation, and are investigating the details while communicating directly with the guests involved to try and make this right. Alaska Airlines has a zero-tolerance policy for discrimination of any kind, and our employees value inclusion for our guests and each other.”

David Cooley did not immediately respond to Fox News' request for comment.