Speaking to children who don't exist yet, the speaker tries to set out the kind of parent they hope to be. They admit they aren't perfect, but promise to try, and they invite the children to come to them whenever something goes wrong. Each stanza explains what a parent's "no" or "yes" might mean: a no is protection, a yes is "good enough," and a dislike of a partner comes from noticing something suspicious. Each time, the speaker adds that they can talk it over.
The last lines change the tone. The speaker reveals they experienced mental abuse from people they call toxic, and they fear their children could turn out like them. The earlier gentleness now looks like an effort to break a cycle. The mood is earnest, tender and a little anxious, with a raw honesty in the plain, unpolished wording. The speaker wants to be a safe, open parent, and is worried about the shadow of their own past.