The term “enforcing boundaries” implies that cooperation is needed from our loved one.
The truth about boundaries is that they are simply ways that we choose to participate or not. There is nothing cooperative about them at all.
For example:
If your partner spends too much on the joint account for personal items, you open separate accounts and close the joint one.
If you don’t want to hear yelled insults, you politely leave the room.
If your spouse wakes you up in the middle of the night to argue, you sleep elsewhere.
Yes, these can be difficult to do, but the only one “enforcing” them is you.
https://bpdfamily.com/content/setting-boundaries