The couple's absence is said to have been a serious reason, reported Radar online.
"It was disheartening to learn that Andrew canceled on the Oscars. If it were a fight or something between them one would have just came without the other, but this seemed to be more of something going on with one of their families," a source said.
Emma Stone, 25, had a long standing family commitment in Arizona.
"With Emma, it's all family first. And Andrew is so devoted to her that he wouldnt just leave her in New York dealing with some sort of crisis on her own," the source added.
Emma Stone's mother, Krista Stone, was diagnosed with triple negative breast cancer in 2008 a case that is known to be highly aggressive and tough to treat.