brood about (someone or something)
To worry, fret, or obsess over someone or something. Quit brooding about that fight you had with your girlfriend and just talk to her already! Recent financial losses have the boss brooding about the future of our small company.
brood about someone or something
and brood on someone or something; brood over someone or somethingto fret or be depressed about someone or something. Please don't brood about Albert. He is no good for you. There's no need to brood on Jeff. He can take care of himself.