We know that Harry's love for Murphy was true because it burned Lara when in PT as they were stripping to go down the laundry chute.
I'm sure Mab is aware. She wouldn't miss details like Lara wearing gloves to give the castle keys to Harry. She's not counting on that protection though, she could care less if they consummate the marriage as long as the alliance goes through. If it does have to be consummated for "reasons" then she's counting on Harry, Lara and Molly(I'd say this is part of the arrangements but that is debatable) to work something out.
I'm sure Lara knows if the protection continues after Murphy's death. It's bound to have come up before.
It's not unfaithful to move on a year after Murphy's death. Harry has a stronger than normal libido due to the Winter Knight Mantle and will have plenty of offers and opportunities. A one night stand or even a short term relationship would be the simplest way to resolve the dilemma, but Jim won't resolve that plot point without some handwringing. After all, losing the protection would place Harry in more danger.
The real twist would be if they fall for each other after facing a year of adversity. It makes Harry's life more complicated and passes the Harry's love interest doom flag to Lara.
