The ABC News anchor acknowledged the relationship in a note addressing her health and reflecting on 2013.

Good Morning America anchor Robin Roberts publicly disclosed her sexual orientation in a Sunday end-of-the-year note addressing her health and reflecting on her recovery from a bone marrow transplant.

"I am grateful for my entire family, my longtime girlfriend, Amber, and friends as we prepare to celebrate a glorious new year together," she wrote in a Facebook note. "I am grateful for the many prayers and well wishes for my recovery. I return every one of them to you 100 fold. On this last Sunday of 2013, I encourage you to reflect on what you are grateful for too."

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It was the first public mention the ABC News anchor has made of the relationship, according to CNN's Brian Stelter, author of a book chronicling GMA and NBC's Today anchors, Top of the Morning.

Shortly after the note was posted, ABC News released a statement: "We love Robin and Amber, who we have all known for a long time. We were so touched by her Facebook message today and so thankful for all the loving support she has in her life."

Roberts, who took a medical leave from ABC News to undergo a bone marrow transplant in August 2012, returned to GMA full-time this September. Earlier this month, the anchor and the network agreed to a new ABC News deal, sources had told THR.