You absolutely can't read this as a stand-alone; the continuing fight of the Order against Dragos comes to ahead here.
The main couple of Hunter and Corinne are honestly only 10-15% of the story, the majority is bringing the Order and Dragos to ahead. This is done through many different POVs, with Lucan and Sterling Chase being the majority. Sterling Chase fighting going Rogue, is a good 30% of this with him almost feeling like the main character (his book is next).
I love the world building and was completely into all the arc and threads coming together and weaving in and out. I was pretty disappointed in this as Hunter's story though. As I said, we barely see his and Corinne's romance, and I don't think we got to really delve into his character.
So yeah, read this as just a world-building bridge in the series and the continuing war against Dragos and definitely not for the romance.