In over your head.
In over your head.
Being "in over your head" describes a situation where someone is too involved in a difficult matter or circumstance, beyond their ability to manage. It’s like swimming in a pool that's too deep—finding yourself unable to touch the bottom can be overwhelming and scary. This phrase is commonly used to express being overwhelmed with responsibilities or facing challenges that are too difficult to handle alone.
He's in over his head.
He is overwhelmed and struggling.
Taking on that complex project left him in over his head.
Taking on the complex project left him feeling overwhelmed.
She thought she could manage the workload, but she's in way over her head now.
She thought she could handle it, but now she's struggling a lot.