Dr. John Gottman has been studying couples for over 20 years and has concluded that the biggest single predictor of divorce is when one or both partners show contempt in the relationship. There is absolutely no respect left at all -- only negative judgement, criticism, or sarcasm thrown at each other.
Here are four ways you show contempt:
"You" language. "you should...," "you need to...," "you have to...," "you'd better..."
Universal statements. Using the words "always," "every time," "such a," and "everyone." "You always leave the toilet seat up," for example. "You're such a slob!"
Tough on the person, soft on the issue. "You are so stupid" instead of "you're a smart person, and what you did this morning was not very smart."
Invalidate feelings. You notice emotions, positive or negative, coming out of a person, and you either discount them, or ignore them completely. "Your concerns are meaningless to me!" "You're blowing things way out of proportion."
... Is it too late to fix your problems? No, but both partners need to recognize what's really going on and be willing to fix it.