When fighting is unrelenting, to the point where there are very few minutes of calm, take it seriously. Fighting about fighting, or not fighting fair, are both signs that the battles have grown big enough that they need to be addressed.
Some couples become so exhausted by fighting that they simply stop, but that doesn't mean that all is well—far from it. In these cases, they often stop sharing things with each other altogether, and have zero ability to bring up any sort of disagreement because they know that it will just spiral out of control.
Your partner should not have to be your only cheerleader, and there may be plenty of types of news—an amazing bargain on that item you wanted! some good words from the boss who's hard to please!—that you naturally share with another friend first, perhaps because that friend has a mutual interest or is closer to the situation
It's a classic problem that has spelled the end of many a marriage: Counseling is clearly needed, and yet only one person is willing to take that step.
Romantic relationships are like friendships in this way; spending time together may not always be fulfilling, but it shouldn't be consistently draining over long periods of time.
It's particularly difficult to begin to work on a problem when there is a total disagreement about what that problem is. This isn't insurmountable, as professional help can typically give insight into the roots of the issues.
There are many tempting reasons to stay in a dysfunctional relationship: financial security, avoiding temporary disruption of children's lives, fear of dating again, or even just the inertia of not wanting to move out.
Similar to a total lack of fighting, a completely detached and superficial civility is often a sign that both partners have checked out.
Subtle misrepresentations of who you are can add up over time. And if it has gotten to the point where your partner could realistically endorse the cliche of "I don't even know who you are anymore!" then that is a sign to take seriously.
Trust is the foundation of a committed relationship, and a lack of it hollows out a relationship from the inside. If it is truly able to be built back up, both partners need to be committed not only to the repairing process but to fixing the root of the problems that led to the breakdown of trust in the first place.