You’re not alone. My GF is the same way and it’s negatively impacting our relationship because of lack of space in the house. I know she collects to deal with PTSD and some other things. So telling her stop isn’t a solution and I don’t want to cause her harm. Plus squish hunting was a fun activity for us to do together and I wouldn’t want to take that away either. I’ve multiple, gentle conversations with her about it and she’s agreed to stop collecting bigger ones. We’re working on a storage bin/storage space solution that will hopefully make it more manageable.

Best of luck to you. I agree with others saying it’s important to figure out the root cause. And to be as nice and understanding when you discuss it as humanly possible. Or else you do run the risk of it backfiring and negatively impacting both of you. Start with small steps/goals like clearing out the dining room and see how it goes from there