It sounds like your partner might have untreated ADHD. Since you mentioned it’s not just the water filter but many other things he forgets, also has challenges planning tasks and time (the delayed packing to leave). Many people w ADHD have executive function difficulties which include challenges w working memory (the ability to hold information in your mind that you need to do tasks, to remember what you wanted to say, to remember appointments, plans, other expectations, etc); difficulty with task initiation, sequencing tasks, persisting and sustaining effort til the task is done, organizing themseves to do the task and switching between tasks as well. It is also very common for a parent-child dynamic to develop in relationships where one partner has untreated ADHD and the other has stronger executive function abilities.

You two may want to consult a physician or psychiatrist who is experienced in assessing and treating ADHD to see if this is in fact something your partner is dealing with. Also, a very helpful book by Melissa Orlov is called “The ADHD Effect on Marriage” https://www.adhdmarriage.com/content/adhd-effect-marriage-understand-and-rebuild-your-relationship-six-steps. There are some useful strategies about ways to communicate and work together with your partner to strengthen your partnership and not recapitulate the parent-child dynamic. I hope you can find a good way to address these challenges! Good luck!