NeverQuit-
I started to "get" boundaries better when I realized they were for me, and me only.
It also helped me once I got this to realize that I did not have any control over everyone else.
For example I had to put a boundary in place that I was not going to participate in activities that were typical places my loved one got drunk (parties, dinner etc). Prior to that I drove seperate vehicles so I could always leave (which was also a boundary).
Other "boundaries" were me trying to control. I had to let those go.