If nobody ever explained this to you, if someone you see a lot does something you like and you never ever tell them that, they might think you don’t like them or don’t like the things they do for you.
If you like your sister’s cooking and have never ever told her that, she may very well think that you hate her cooking. If you like it when your friend drives you places and you never ever thank them, they might think you’re not grateful even if you are. If you like it when your partner does this or that thing for you they won’t know that unless you tell them.
Tell people in your life hey thanks for driving me, that was a great dinner, I like your singing, thanks for helping me with that. They don’t automatically know that you appreciate what they do.