can't help but
can't help but {informal} also {formal} cannot but {v. phr.}
To be forced to; can only; must.
When the streets are full of melting snow, you can't help but get your shoes wet.
When a friend gave Jim a ticket to the game, he couldn't help but go.
When a close friend dies, you cannot but feel sad.
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Source: A Dictionary of American Idioms
