Hi Kim, I really liked these lines because I could connect to them:
We had a blast picking out the saddest
marked down Charlie Brown tree
‘Cause once we decorated it with love,
it was pretty as could be

Where I think you could be stronger is developing your hook some more, making the chorus stronger and more descriptive. As a reader/listener, I was left asking why? Why is the person not there anymore? Why did he/she leave? Death,, cheating/divorce, etc? I feel like you haven't told the whole story yet, ie more development with the details. Good start for sure, but I try and develop it even more. GL!