Walking under the moonlight and gazing at it is one of my favorite things to do!
If you’re a very visual person then yes, not being able to see the moon can make you sad! Me too! 
I recommend that you place an image or representation of the moon on your altar, Maybe a statue of the goddess Selene/Luna, or have a piece of Selenite (moonstone) to hold onto. Close the blinds and light a candle. 
Also a mirror could represent the moon reflecting light and shining down onto you.
When you can’t find it, craft it! 
PS: Welcome to the Forum, @margot!! Make yourself at home!