As far as I'm concerned, it's a chicken-and-egg issue. What I can tell you is that physical clutter and relationship problems seem to go hand in hand, and I don't believe you can fix one without fixing the other. Getting rid of the physical clutter is, as they say, another story, and it's one I've already told in my book It's All Too Much: An Easy Plan for Living a Richer Life with Less Stuff.
I'll just boil it down to the basics. The clutter-clearing process I use is consistent across emotional and physical clutter.