I just read a legal document shared on Facebook about Kate Walker, author of many many Harlequin novels and 12 Point Guide to Writing Romance being a defendant in an infringement case.
To think that she was accused of copying someone else's work, to me, is ludicrous!
What i got from the legal mumbo-jumbo was basically the accuser's unpublished work had a similar theme or trope as that of Kate Walker's work.
I recently read a fantastic new author's work and thought "hey that sounds a bit like my idea" - our characters are by no means the same, their struggles aren't the same, but my small 10,000 word first draft is about best friends turned lovers which shared the same trope - that's it!
So, similar ideas do not mean copyright infringement - using exact phrases and words as someone else is.
Have a read of the legal document here
And to Kate Walker - thank goodness the case was dismissed!