Not having read Heal Me, I was missing some of the backstory for the events at the beginning of Complete Me, but that's my own fault. It didn't affect my reading experience or deduct any stars from my rating.
While I do wish we were given more of Xander and Kaino getting to know each other (they had each previously and separately dated Bjorn), I did enjoy their relationship and watching them all fall in love with one another (again for Xander and Bjorn, and Kaino and Bjorn). 
No one was left out of this polycule, not really. Xander struggled with it when Kaino and Bjorn had alone time one night when his teaching job took precedence, but a little bit of pampering, love, and attention (and a healthy conversation about what took place that night) put his mind at ease. 
The communication between these three was open and healthy. Given that they started using rope play and Kaino was the leader for their scenes, the communication (and consent) was needed and appreciated.
Demi Rep✅
Communication✅
No 3rd act breakup✅
Low angst✅
Spice🌶🌶🌶🌶
Kink➰
I received an ARC from the author for my honest opinion and review.