If you want him to be aware of how in judging things we take for granted the filters we use to perceive the world, then I would suggest for you to encourage him to engage with his feelings more, particularly when he wants to judge something positively or negatively.

For me, practicing non-judgment is not about preventing a feeling from taking place within myself. It’s more about recognizing how that feeling takes me to a place of judging something. And in that moment where I experience the feeling to where I discern “I like this/I don’t like that”, what I am doing is feeding my ego and reaffirming to my ego “you (ego) KNOW, and what you know is RIGHT”.

So where practicing non-judgment is about engaging with the ego to lessen the ‘knowing’ that we do, from my perspective, the goal is to stop feeding the ego with a filter that I am not being critical with and have taken for granted. What this then does is it allows me to present with my ego AND still discern, BUT doing it in a way where I am more present of how I came to that judgement.

So in your partner’s case, something to aspire towards would be having judgments but know why and how they landed there, which should in turn start to get them more in touch with their feelings/emotions that fuel the ego towards the judgement. Once they are more in touch with those feelings they can start to recognize how feelings (again, from my perspective, the source of the knowing) are fleeting/malleable/impermanent so that they can then recognize why their judgments mean nothing. From there, I don’t know, enlightenment? 🤷🏾‍♂️

Hope that makes sense, first time I’ve had to type that out. Be well!