How many times have we heard, "we were on a break?"
IMO it's not a break if the sheets are still warm.
IMO it's not a break unless both parties know it.
I don't know the status of their relationship, at its best or its worst, but it looks like it had a lot of entanglements (living together, working together). Great if it works, challenging if it doesn't. Can't slam the door and walk away if you have real estate, businesses, projects in common.
I wonder if KA hadn't made the decision to leave the relationship, even romanticizing the seeya with the fairytale of herself living the dream on a beach, solo.
I could be wrong but I get the feeling that KA acted out of vengeance -- pure passive-aggressive vengeance. She may have started thinking the victim was an interloper, only recently discovering she herself was being played. So how to hit him where it hurts? Take away both women. Maniacally passive in regard to him, viciously aggressive in execution.
I think what we're seeing on her stone face is smugness. I think she thinks they got what they deserved.
Leaving her to wipe her hands of them both and start her new life of "zen". She's a poser. An shape shifting embodiment of arrogance, entitlement, narcissism, confidence, delusion, retribution...
Beautiful on the outside, fed the ugly inside.
JMO