Bluechair, my social worker friend says the same thing you do about the rubber band thing. I find it helpful right now - I'm loathe to give it up just because I'm trying to take care of how my wife is feeling, don't snap the rubber band around her because it makes her mad? That seems.... codependent somehow.....
A couple of things:
1) a social worker who is a friend is incapable of giving you neutral advisement. The point of therapy is having a port in the storm by someone who is advising you and guiding you in a professional capacity. You can't substitute friendship for therapy.
2) Personally, what is co-dependent is marking every negative feeling for your wife at your wife in the moment you are feeling it, including in marital counseling. If someone did this to/around/about me, I would not hesitate to cut them off. It's extremely passive aggressive. There are way more healthy ways to accomplish this goal in earnest that don't involve letting everyone around you know how irritated you are with them. It's a silencing technique, and I would argue this is abusive.
EDITED TO ADD: IME the rubber band technique is to stop unwanted thoughts in a short term capacity. Generally Al-Anon -- and by extension SR -- advises something else entirely, which is feeling the thoughts, grappling with and dealing with them in a complete and holistic way by learning new methods of coping with our feelings. I'd also argue that the rubber band method is inappropriate method for what you say you want to accomplish. That's just me. I found that I got the most out of participating here and in counseling when I started integrating what people were telling me into my life, starting trusting the process, and stopped trying to fight the process so much.