The message, which follows Roberts' battle with a life-threatening illness, is the first time the "Good Morning America" anchor has publicly acknowledged her 10-year, same-sex relationship with Laign, a massage therapist from the San Francisco Bay Area.
Roberts' post was confirmed by ABC News spokeswoman Heather Riley.
Sunday was the anniversary of Roberts' 100-day milestone following a bone marrow transplant in September 2012 for treatment of myelodysplastic syndrome, a rare blood and bone marrow disease.
In May, Grand Central Publishing announced Roberts, one of the most popular figures in morning TV news, will write a memoir about her battle with MDS and the life lessons she continues to gather following her return to "GMA" last February.
