Sometimes the killer of relationships isn’t a lack of trust, a lack of communication or arguing with your significant other. It’s simple indifference.

A relationship can survive most things if both people involved in it are committed to the other person and act with respect toward the other. It can survive the death of our parents or the birth of a child. It can sometimes even survive an indiscretion (although such a behavior shows a shocking lack of respect for one’s partner). It can survive layoffs and career changes, of going back to school, or buying your first home together. It usually can even survive the wedding, one of the most stressful things adults go through in their lives.

A relationship can survive angry tirades and arguments that span endless lonely days and nights. Anger means you care, even though you are caring in such a way as to negatively affect your partner. Relationships can, with some difficulty, survive lack of communication or communication problems.

Communication is one of the key ingredients to a successful relationship. Successful couples don’t always agree, but they let each other know what’s going on in their lives, and how they’re feeling (especially when their partner does something that sparks a particular emotional response in the other person). Relationships survive with poor communication, although they tend not to be happy ones.

What a relationship has real difficulty surviving is when two people have gone into “autopilot” mode and become indifferent toward one another. When you’ve given up on emotion entirely, when you feel nothing toward the other person, that’s a difficult thing to come back from. Communication appears to be taking place, but it’s just shallow talk — like two acquaintances might do who just met on a plane.

Think about it. Even when we argue, we communicate with the other person — we express our disappointment, hurt or anger for some perceived slight or harm. When we distrust our significant other (for whatever reason), it hurts because we care enough to want to trust them in the first place. Cheating hurts most people not because of the act itself, but because of the basic violation of trust and respect in the relationship. The fact that it hurts, however, signals we care. If we didn’t care, it wouldn’t hurt us.

Indifference is not caring what the other person does in a relationship. There are no arguments, so everything may seem okay on the surface. Arguing stops because you don’t care if you were right or felt hurt by another person’s words or actions. Trust isn’t an issue, because you don’t care about earning or having the other person’s trust (or trusting them).

You interact every day in a vacuum where everything seems okay, because neither of you cares whether it is or not. It’s a perfect illusion that you both have silently agreed to live. But it’s not a relationship at that point anymore. And it’s hardly living.

Ideally, relationships help us not only love another human being, but grow as a person. They teach us lessons about life that otherwise would be difficult to learn, lessons about communication, listening, compromise, and giving selflessly of yourself and expecting nothing in return. Of learning to live with another human being and all that entails.

When we’ve closed ourselves down in a relationship, we’ve shut off caring. We’ve shut off growth. We’ve shut off learning. And we’ve shut off life.

Indifference doesn’t have to be the end of a relationship, however. If caught early enough, it’s a warning sign that something has gone horribly awry with the relationship, with caring about the other person and your feelings for them. If both people in the relationship listen to that warning sign and seek help for it (for instance, with a couples counselor), there’s a good chance the relationship can survive if both people want it to.

Beware indifference in a relationship. If your automatic response to your significant other’s question always seems to be, “Whatever,” that may be a sign that it’s creeping up on you. If you still care about the other person in your life and the relationship’s future, you’ll listen to it.