puzzle over (someone or something)
To think about or consider something, usually at length. After puzzling over the experiment all day, I think I've figured out where we've gone wrong.
puzzle over someone or something
to consider or ponder. I can't puzzle out the mean—someone or something. Anne is a bit strange. I've spent some time puzzling over her. While I was puzzling over why she had slapped me, she did it again.