watching the mv over and over another thought about how this is related to Tao, Kris, and Luhan. . during the opening, the members are shown laughing and playing happily all together.
but things started to go wrong, members start disappearing and the others become upset. This makes me think of the members were upset when Kris first left, and then when luhan and tao followed suit. I especially connect this reasoning being that Lay, the only Chinese member left, is the first to disappear.
Suho and chanyeol were in a fight and ended up hugging each other on the ground crying referencing probably towards exos "fight" on moving on without the lost members emotionally and mentally.... also maybe it means the fight the ex members had against SM???? anyway suho and chanyeol hugging it out is the acceptance of what had happened in the past and realization that they need to continue on without the ex members.
The members are then shown being happy again, showing that they will move (or have moved) on. They are all together once again sending the message that even though some may leave, they'll always be together in heart. And the ending scene of suho and chanyeol lying side by side in the snow is symbolism of resolution adding on to that message
here's the link for the first part of my theory Sing For You Explanations and Theories http://www.vingle.net/posts/1268364?shsrc=v