First of all:
There are no Line feeds in EPUBS (XHTML). The ones in code are just to make it easy on the coders eyes
I will assume you have 'broken lines' (The sentence is in multiple pieces)
Unwrap factor should get smaller .4 is a good starting point
If there are MARGINS between whole paragraphs, then the style needs to be adjusted
And the horrible 'empty Paragraph' (because someone did not know about top/bottom margins.
If this book is as messed. Ask for your money back. There are just to many folk calling themselves e-book formatters that have no clue to the basics