
That’s her/his/their/your problem
Personal Responsibility
Suggests the person must deal with their own issues, without expecting help.
If he lost his keys, that's his problem.
Blunt Dismissal
Indicates a blunt or unsympathetic dismissal of another's concerns.
She missed the deadline? Well, that's her problem.
Conversational Cue
Signals the speaker's unwillingness to discuss the matter further.
You don't like my decision? That's your problem, not mine.