Cox, 59, and McDaid, 47, celebrated 10 years together with a sweet montage video posted to Instagram on Monday (25 September).
The video, which is set to the tune of Sheeran’s 2017 hit song “Shape of You”, comprises several photographs of Cox and the Snow Patrol musician over the years.
The caption goes on to explain how it had been Sheeran who first introduced the couple 10 years ago.
In one segment of the video, Sheeran and his wife Cherry Seaborn are seen sitting on a sofa with McDaid. The singer serenades them both with an acapella version of “Shape Of You” with lyrics tweaked to make the song personal to McDaid and Cox’s relationship.
Sheeran wrote the hit song with McDaid. The pair also collaborated on Sheeran’s song “Bad Habits”.
“I know your heart is falling too. Johnny’s in love with your body,” sings Sheeran in the clip. “And last night, you were in his room. And now his bedsheets smell like you. Every day discovering something brand new. Johnny’s beard is the shape of you.”
The video concluded with a final snap of Cox and McDaid with the message: “Happy anniversary J”, accompanied by a heart emoji.
Celebrity friends of the couple were quick to congratulate the pair on the milestone.
Leslie Mann commented three heart emojis, while comedian Ali Wentworth added: “Awwwww… So much love!!”
Cox and McDaid have been together since 2013, getting engaged in 2014. They called off the engagement a year later but reconciled in 2016.
Cox shares a daughter, Coco, with her ex-husband, actor David Arquette whom she divorced in 2012.
Sheeran is gearing up to release his forthcoming album Autumn Variations, which will feature a track – titled “American Torn” – inspired by the hit sitcom Friends, on which Cox played Monica Gellar.
Announcing the surprise album in an Instagram video last month, the singer said that the record was inspired by the “highs of falling in love and new friendships among lows of heartbreak, depression, loneliness, and confusion”.
Autumn Variations will be out on 29 September.