A few things have stood out to me so far. First was this section:
That's been one of the "hard truths" that I've seen practiced more in non-monogamy circles, than I did in monogamous ones: namely that it's more pragmatic to own your own feelings, than to hold someone else responsible for them via blaming. This isn't equivalent to giving malfeasors a free pass by the way: it's still appropriate to hold actors accountable for the foreseeable consequences of their actions, including the emotional ones.
I also disagree with the claim that feelings are chosen, at least on an incident basis (I buy more into a cognitive behavioral therapy-based model, where an expectation or belief is what connects a trigger to an experienced emotion). However, because most of the variables that drive the presence and intensity of emotion are within the experiencer rather than the trigger actor, it is more pragmatic in the narrow case of mature adult peer relationships, for the experiencer to own their feelings rather than to blame those feelings on a partner. Through therapy and other means, over time one can change how and whether they respond to the same stimulus. They can also change the environment, communicate and enforce boundaries in the relationship, and deescalate: all of which are preferably empowering, relative to the "you made me mad" power handover to the partner.
It also feels less mature to blame one's feelings on another, rather than claim ownership of them, especially when that partner claims ownership of her own feelings: they are then responsible for an unequal ratio of feelings of the pair (say, 60%: 50% their own, and 10% the partner's). Even though the underlying truth is that both the trigger actor and the experiencer share in the causality pie, the empowerment assumption is more accurate and more useful than the victim assumption, especially with respect to problem solving for similar trigger-->emotion cycles in future.
It also results in a more empowered community, where ongoing relationships and agreements are more often the result of deliberate, considered choices with meaningful alternatives: rather than the defaults and roles and assumptions that prevail more often in monogamous communities, relative to partner-triggered emotions. It also gives members of that community more autonomy and individual identity (which can blur into codependence otherwise).
Second passage that stood out to me. This part hit close to home:
Just last night, after frustration-induced yelling at my kids, I reminded them an hour later when things were calmer that I'm responsible for my feelings and not them. And the coffee that they spilled, or getting distracted for the umpteenth time during the night routine, doesn't mean that they did something wrong or that it's their job to help me calm down. Not sure how deep the message sunk. 😆