It's okay to feel sad.

Advice on how to feel "happier" is everywhere. There have been hundreds of books written that suggest ways you can (and supposedly should) avoid feeling sad, angry, embarrassed, or anything else aversive. Even the way we label these emotions communicates they are something to be suppressed or avoided--we call them "negative" or "bad" emotions. But in what ways might that be a significant disservice? By avoiding or suppressing these emotions, we do not give them the chance to tell us something important, sometimes about ourselves or our environment. All emotions have a job to do. They help us achieve our goals and direct us toward what is important. It's okay to feel sad. Let it tell you something. Working with a psychologist in therapy may be a helpful way to learn how to accept and listen to these challenging emotions!

https://www.psychologytoday.com/articles/201501/beyond-happiness-the-upside-feeling-down?collection=167224