At first glance denial might seem like an immature behavior, like pretending something isn't a problem when it clearly it is and others seem to see it for what it is. In a closer look, consider how psychology defines denial as a defense mechanism to avoid painful realizations. This inability to take in the reality of what is happening is actually an unconscious mechanism to protect the individual from painful or uncomfortable thoughts, feelings, and experiences. Typically, the stronger the denial, the more is at stake emotionally for the person.
Codependency is an ever-present concept in the language of recovery. Partners, family members, and friends of people who struggle with problematic substance and behavior are typically automatically assigned this label. It is assumed that anybody in a close relationship with a person with an addiction is, by definition codependent.
This is a really good question to grapple with, one that can be answered from many perspectives. Let's start with some definitions found in some mainline professional addiction treatment sources.
Couples impacted by an addictive disorder have a lot to process. However, not getting stuck in the future or in the past does not mean that you do not acknowledge the past, or its consequences.
I was asked to write a response to the above question in the Thrive Global article series, "Asking for a Friend". This is a question that many people struggle with, not knowing what to do when there is evidence of a drinking or other drug use problem with the person they care about.