Is it up to him? I mean Mab can plot or Lara can plot, drug Harry, get some woman to go to bed and have sex with him when he is vulnerable... That's the end of his protection.. Now Mab might want to keep her Knight, but in revenge for what she thinks Harry did to Thomas.. She said as much on Demonreach, and Harry knows if she can she will get her revenge.
My guess is Lara will get even with Harry by making him do something, and most likely something that Harry won't like, in order to settle the balance between them. Whatever Lara will demand of Harry, it will be something reasonable from the standpoint of "getting even" but something that will probably make Harry look bad, especially to the White Council.
I think Lara wants to use Harry, not destroy him; at least on a conscious level. Of course, Lara's demon doesn't have a problem destroying anyone and can sometimes do what it wants regardless of what cold calculation would say is the best or smartest move to make.
I disagree about Harry being suicidal angry at Mab at the end of Battle Ground. He isn't, actually he understands on some level what she is trying to do and accepts alliances cemented by marriage. That doesn't mean he has to like it. Molly is the one that is really angry, most likely because she knows the real reasons behind it, hence the look she gave Lara after she and Harry battled the Kracken, the look that Harry admits now that he missed.. So stay tuned it isn't over and I doubt that there will be wedding bells..
Your post got me thinking. We know that Mab doesn't want Lara to devour Harry, but perhaps she doesn't have a problem with Lara controlling Harry. If Mab has enough leverage on Lara she could control Harry by proxy. Harry would still have free will; more or less, because it's not the same thing as complete mind control, but with Harry addicted to Lara, Mab wouldn't have to take the time to find ways to force Harry to do her bidding. If Molly even suspects that is what Mab is trying to achieve it would explain her anger.