Your boyfriend seems to be angry at you. He's acting rude to to you, and you don't know why. You want to let him know that you're annoyed by his behavior, and you say this to start an argument.
What's your problem?
This is a phrase that you use to start an argument with someone who's acting angry or rude. "What's your problem?" means "Why are you acting that way?" But when you ask someone "What's your problem?" it sounds like you're criticizing them, so it usually makes people get angrier and start to argue with you.
People usually say "What's your problem?" to family members or people that they're in a relationship with. But some people would also use this when talking to a stranger who really made them angry.
You should not use this phrase to ask about someone's health. If someone seems to be sick, ask:
Also ask "What's wrong?" if someone seems sad, frustrated, or frightened.
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