This is the most balanced, wholesome and rare thing in most cuckolding stories. However it's not the most fun, I love the darker sides of Nat, with her cheating and 'lovingly' bullying Ethan into cucking.
I agree, the vanilla-type cuckolding can get stale and boring pretty fast. It's also hard to work on character development if everything is just the american dream and everything is perfect in their relationship.
I want some drama, I want Nat to find her own desires going forward and I wanna see how Ethan copes with that. Nat can love Ethan but at the same time find some pleasure in humiliating him about this cuckolding lifestyle. I want Nat to test the waters and see where Ethan draws the line and then maybe she can move it herself with a little bit of manipulation.
If it doesn't work she can always fall back on "but this was your desire to begin with, what about my desires?".
Ethan would budge, and now the boundaires are muddled. Makes for more interesting story when the characters are walking a thin line between what's acceptable and what's not. Nat can still love Ethan, but she doesn't see him the same way as when their marriage started. She doesn't look at him and think "that's my alpha male husband", but she probably never did.
The fact that she loves him is irrelevant in this new sexual landscape they are now navigating.