"It's about my last conversation that I had with him," the Glee star revealed to Seventeen. "I spoke to a woman who lost her son, and she mentioned how grateful she was that the last words she said to her son before he died were, 'I love you.' Mine were that as well. [The song] is just about that. There are lots of different emotions—if you could see this person again, what are the things you would want to say to them? It's a personal story."
Michele's debut album, Louder, drops on March 4.
"It's been seven whole days/ Seven whole days since you paralyzed me," the 27-year-old croons at the beginning of the beautiful ballad. "It's been seven whole days since you lost your fight/ And I can't get the last words that you said/ Can't get those words out of my head/ Seven whole days/ Seven whole days and four words."
She continues on the emotional track: "Was just a week ago, you said, 'I love you, girl'/ I said, 'I love you more'/ And a breath, a pause/ You said, 'If you say so'/ 'If you say so. If you say so.'"
Michele spoke to Glamour U.K. about the late actor and how she feels he is "watching over her."
"Every day when I go running, I feel like he's pushing me to run harder," the singer explains.
Michele shared that the couple had big plans before his untimely passing and added that she is grateful for the time she had with him.
"We talked about a lot of things," Michele said. "We talked about children and what we would look like when we grew old and who would be fat and how we would stay thin. We talked about where we wanted to go and what we wanted to do. We were done. We were it. When you're at that place in your life with someone, you talk about everything."
Grab your tissues and listen to "If You Say So" now.