I think positively of my partner.

An unwashed pan on the counter can be read two ways: they don't care, or they were exhausted. Both stories fit the evidence. You pick one, usually without noticing that you picked.

Most resentment gets built out of a long run of these small interpretive choices, each one perfectly reasonable on its own.

Thinking well of someone is not naivety. It is choosing the more generous reading when the facts genuinely permit it, which they do far more often than an irritated mind will admit.

Next time you catch yourself narrating their motives, notice that you are the author, and then consider the other draft.