Sadness for a two-year old

Makili is very interested in the concept of sad. He constantly asks if someone in a book or a movie is sad. I was just listening to Pandora and a Dolorean song. Makili asked if he was sad, and I said "yes, he's sad." A few moments later he asked, "did his mama leave him?" I chuckled and said, "no, he loved a girl and the girl left him." A few minutes later he asked, "did the girl have to go to work?" He makes me smile when he's not driving me nuts.