"If you think their messy room is hard to look at": This part of the quote acknowledges the inconvenience or annoyance that a messy room might cause.
"Just wait till it's empty": This is the main point of the quote, emphasizing that an empty room, possibly due to the person's departure or absence, can be far more emotionally challenging.
In essence, the quote encourages us to prioritize the presence and company of our loved ones over trivial matters like the cleanliness of their living spaces. It serves as a reminder to appreciate the people in our lives while we have the opportunity, as their absence can be much harder to bear.