"We were reading his romantic short stories."
Translation:Ми читали його романтичні оповідання.
Short stories --> короткі історії is for sure correct, thanks for pointing it out. Added it.
I've noticed many times that plural words end in і/и, and романтичні is obviously not an exception. Is оповідання one of those exceptions, or is there a way to differentiate between "short story" and "short stories"?
Оповідання is both singular and plural: одне оповідання, два оповідання (in nominative). Most of the other nouns ending with -ння are not countable, so i can't think of a rule/pattern, sorry :)