problematic -
making great mental demands; hard to comprehend or solve or believe; "a baffling problem"; "I faced the knotty problem of what to have for breakfast"; "a problematic situation at home"
difficult,
hard not easy; requiring great physical or mental effort to accomplish or comprehend or endure; "a difficult task"; "nesting places on the cliffs are difficult of access"; "difficult times"; "why is it so hard for you to keep a secret?"
problematic -
open to doubt or debate; "If you ever get married, which seems to be extremely problematic"