And this is exactly problem. I disagree strongly with you. It's conflict of two different moral systems.
You and
@FollowingHim are all seeing how she is bad bad bad wife just because she wasn't completely doing what her husband expected.
I expect wife to do what is in her best interest. Why? It's called being human. And because for me trust means not doing what I tell you, but act in my best interest and tell me literally anything without fear.
And I truly mean literally anything. Including worst parts. Especially those.
There is a just slight problem. You can't punish person for telling you truth. If he/she senses that being sensitive is path to punishment forget about real honesty.
So wife must be rewarded.
It's also reality that woman-woman "action" is by far least "problematic" sexual activity and don't forget: lesbians aren't real. Is least possible "crime".
This can't be longish affair. If this lasted several years he would be by way more pissed. Look at tone. He isn't angry, he is: It's unbeliveable.
What is also most not considered is that wife acted in husband's best interest. Almost certainly wife started having feeling for Charlotte or opposite, something started happening and girls started planning how to turn this into menage a trois. They probably did deed several times.
What is interesting is that nobody here has considered is husband being trustworthy. You are in good company. Same thought didn't occur in husband mind. He can't be blameless. Why wife didn't feel confident to tell him right away, but girls need to search way? This is on him only.
What she has done is female version of man finding lover, telling wife "Lord is OK with polygamy", wife finding truth. While we both agree this isn't optimal approach, it's also not a best way to correct thing. But it's a try to correct things. And this counts and doesn't deserve to be punished. In fact it should be rewarded.
In the end, I'm slightly sceptical about whole situation. We don't know whole story. But I what enough she isn't bad person. Nor a good person.
Situation leaves much to be desires, but evil isn't. Just messy humanlike.