Most of us have heard this so many times, it has almost become a meme. Sometimes the speaker is referring to something as mundane as a broken appliance or cranky toddler. Other times, it could be spoken about something as important as a tyrannical work associate who is wreaking havoc on your sanity. Of most concern to me is when I hear this said in a couple's therapy session. It is frequently an indication that at least one of the partners has "checked out" of the relationship, deemed it no longer worth saving.
Many therapists probably want to respond "Oh, yes you did". Yet, reminding the married couple of their vows or discussing commitment doesn't address the urgency of where they are today in their relationship. Typically, a couple will endure a crisis, let some time pass, and get on with routine living never addressing the temporary "bump" in the road. The trouble is that those bumps usually have a cumulative effect over time causing a deterioration in the relationship.
As with physical illnesses, early intervention is key. But whether or not it's too late to salvage the relationship can only be determined with any degree of certainty by seeking help.