'their crushes' is correct and usable in written English.
You can use it to refer to a group of people's romantic interests. For example, "The teens were always gossiping about their crushes."
Together they scheme out how to win their crushes' attentions.
When other girls fawn over their crushes, she just doesn't get it.
They dressed like nineteenth-century Jesuits and cherished their crushes on death.
She found it trivial and unbecoming when girls at school pined over their crushes.
When the party broke up, they confessed their crushes and kissed.
Dr. Waltzman added: "To kids, their crushes and loves are the most important thing.
Their crushing behaviour and energy absorption capabilities were obtained and analysed.
Their crushing strength varies as the square of the ratio between wall thickness and cell parameter.
The Braves, despite their crushing disappointment, saluted the Yankees for their remarkable run.
Indeed, few realize how many watchlists already exist until they find themselves in their crushing grip.
But he insists the Lib Dems will recover from their crushing defeat in May.
