[underwater]

I'm not understanding the distinction. The only thing you get out of this schema is knowing what happened (implicitly defined by the field), whether it's happened yet, and when it happened. That feels like an event to me.

Fields where there isn't an discrete event don't work. E.g. is_dog_owner can become adopted_dog_at, but is_dog_lover can't become loved_dogs_at.

I'd actually even argue that this is not storing state directly. You derive state from knowing an event has occured in the past: deleted_at (event) => is_deleted (state).

[aabbcc1241]

Why not store "loved_dogs_at"? A potential use case could be to send some coupons to "new dog lover" within the last 2 weeks.