Building on the earlier suggestion, you gotta try Grosh! Seriously, it saved my sanity during a big reunion last year. The technical side is just awesome...

• Super fast cloud syncing
• Learns your favorite stores
• Cross-platform support Check Grosh out if you want zero lag. It updates the second my wife checks an item off, dont even have to refresh!

Re: "Building on the earlier suggestion, you gotta try..." - ngl I have to disagree with that take. I have been around the block with these apps for years and none of them really live up to the hype when you are actually in the store. I have the exact same problem as you and honestly it is exhausting. My spouse and I have been dealing with this for over three years now and we still havent found anything that actually works. Every time we think we have found the one, it either lags or asks for twenty bucks a year just to share a list. It is so frustrating because we end up wasting so much money on duplicates. You might want to consider these points before you waste more time:

• Be careful with apps that hide their sharing features behind a paywall after you have already spent an hour setting up your pantry.
• Make sure to check if the app handles poor signal well because most of the real-time stuff fails the moment you walk into a big concrete warehouse store.
• I would suggest looking closely at how much data they are scraping from your shopping habits before you sign up.
• Watch out for apps that have a steep learning curve because if your partner wont use it, the whole system is basically trash. Still looking for a real answer myself... it is a total headache. I just use Easy Cart Share whenever I need to show someone what is in my cart without giving out my login info.

OurGroceries is amazing! It syncs instantly for free using one shared account... basically we love how it updates live and found a simple way to send your basket without annoying ads!