All bottled up...

Lots of things,
all bottled up.
Stressed,
no escape.
Things I want to say,
yet I cannot.
Boiling point,
steam builds up.
When will it all,
just blow up?

Saying goodbye is basic courtesy

No one will stop you if you want to leave, but at least say goodbye. Don't leave without saying a word. It is basic courtesy. It shows that you respect the person(s) who you are walking away from. It would be good if you share your reason for leaving, but no one will press you to share if you do not want to.

Leaving quietly tells people that you either want to hide the reasons for leaving (which means you are not brave enough to own up to and defend your decision) or that you don't respect them enough (they are not worth the time for that simple goodbye). Neither reason makes you look like a person of character.