> I think there's nothing wrong with seeing your partner struggling with something, talking to them about it and coming up with ideas to help them.

There is something wrong here: and that's assuming your partner is the one struggling. In clinical cases of hoarding and ADHD, that can definitely be the case - but all hints, nags and nudges are useless in these clinical cases anyway.

Fact is that in your day-to-day neat freak vs messy partner situation, the person struggling with mess is actually the neat partner and not the messy one. Most messy people I know, and have worked with, are quite content with mess.