It's not all that uncommon for a WW to turn on the niceness after the bomb drop, especially if her H appears to go along with what she wants. I compare it to a mother who makes her young son do something he hates, and she is trying to convince him how great it is. In other words it's as if your WW is saying, "See? It's not so bad. We can still get along and be one happy family".
Going forward, you may notice that as long as you do exactly what the WW wants, she may appear nice from time to time.........until she gets mad at something or even someone else, and takes her bad mood out on you. Remember, she is a user. She expects you to be available 24/7. She will take advantage ever way she can. And, if you tell her "no" or do anything she doesn't like.....then she punishes you by not being nice to you. Her "niceness" is a tool she uses to get what she wants.......or to punish by taking it away.
The WW is extremely selfish and untrustworthy. When she suddenly becomes nice for no apparent reason, it's usually indicative of manipulation at play.......on some level.
Her niceness should not throw the H off guard and think she is having second thoughts about the M. Instead, he can expect her to want something from him. The nice act is her way to butter him before she asks for something. Unfortunately, it works on a lot of H's b/c they fail to see what she is really doing. I've even read some posts from H's who had a good idea.......but would say "It felt so good". That's just pathetic.
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!