The phrase 'In over Your Head' is used when one is too deeply involved with something or someone, or has more difficulties or problems than one can manage. You can use the idiom 'In over Your Head' to advise someone he needs help.

What does it mean to be in over head?

informal. to be involved in a difficult situation that you cannot get out of: Sean tried to pay his gambling debts, but he was in over his head.

What phrase is in over his head?

In over one's head is an idiom that means that someone is involved in something full of difficulty, something that is beyond that person's ability to cope. To be in over one's head means to be unable to deal with a situation.