We tend to think of cheating as sexual, whether it's a one-night stand, virtual sex, or an ongoing affair.

"Emotional cheating" is a particular type of secretive, sustained closeness with someone who isn't your primary partner.

It's one person making a unilateral decision to cultivate nonsexual intimacy with someone other than their primary romantic partner in a way that weakens or undermines the relationship.

Many see this type of connection as having an erotic component to it. Though there often can be an underlying romantic or erotic energy in emotional cheating, it can also occur without the element of romance or eroticism present.

I've worked with couples who feel "emotionally cheated on" by partners who share too much with friends, work colleagues, or even family members—people with whom there's no romantic frisson whatsoever.

Nonetheless, they've experienced it as "emotional cheating" because their partners have engaged in an inappropriately deep, sustained closeness with someone else in a way that excluded them. I've even talked to people who feel their partner is emotionally cheating on them with a therapist!

Because this type of cheating can look "healthy" from the outside, it can be hard to name and confront: non-erotic emotional cheating—a powerful spiritual friendship with a pastor or teacher, an idealized mentor with whom you have an ongoing passionate email exchange about poetry or art, flattering DMs from a well-known business coach on Instagram that have been getting increasingly personal.

The advent of the internet and the abundance of ways to connect with people all over the world has opened up the number of channels available for different forms of cheating to take place outside of a primary relationship.

Many who cultivate this type of closeness defend it with phrases like, "They're just a close friend," or "But you said I should turn to other people for support," or "They listen to me when you're too busy." For this reason, emotional cheating can go undetected while silently siphoning energy away from a relationship and leaving you and your partner disconnected.

One way to "diagnose" whether you or your partner are engaging in emotional cheating is to look at the impact.

Does the outside connection strengthen or weaken your bond with your partner? Does the intimacy you have with someone else—a co-worker, Facebook friend, trainer at the gym, or yoga teacher—support your closeness with your partner or erode it?

Another way of assessing whether emotional cheating may be taking place—particularly if you're the one doing it—is to tune in to how you feel.

Does this outside person temporarily relieve a sense of loneliness but leave you feeling lonelier in the long run? Is your closeness with them something you crave—like a sugar fix—that comes with a lingering sense of guilt when you get home to your significant other?

No single item on this list means your partner is emotionally cheating. But if you're noticing that multiple items on this list are at play, it could be a sign that there's a degree of emotional cheating occurring.

It could also mean that you've stopped prioritizing the intimacy between you and your partner, and it's time to recommit to one another—to lean into your feelings and vulnerabilities, despite fears or obstacles.

Caveat: You shouldn't use accusations of "emotional cheating" as a way of justifying coercive, controlling, or manipulative behavior toward your partner.

What’s the difference between friendship and emotional cheating? The short answer is that with friendships, there are different boundaries than in a primary attachment.

When a romantic partner becomes a priority in your life, it's important for friendships to flex and give, even as they remain present and supportive. This allows more space for your relationship to develop as your main source of closeness and support.

Opening up to depending on a romantic partner fosters bonding, trust, love, and intimacy.

If your partner is emotionally cheating, you might be wondering: Why are they doing this? Is it because they're secretly in love with this outside person? Have they stopped loving me? Is it because there's something wrong? Is our relationship over?

Sometimes, the unilateral decision by one partner to "emotionally cheat" is consciously and strategically made, but more often than not it's about small, cumulative, perhaps well-intentioned, and unconscious boundary slippages—something that a partner thoughtlessly indulges in when they regularly share thoughts, hopes, dreams, feelings, frustrations, passions, or other aspects of their inner world with someone else, unbeknownst to their partner.

More often than not, emotional cheating is a way that one partner is trying to get a deeper need met—or to protect themselves from a feared scenario.

Why aren't they trying to get this need met with you? How come they don't just share their inner world, their fears, and vulnerabilities with you directly rather than cultivating a close bond elsewhere? These are big questions with complex answers that vary.

Maybe they've tried to get close to you, but you've been dismissive, judgmental, or unavailable. Maybe they themselves are afraid of driving you away with their "neediness." Maybe depending on you scares them. Maybe they're mad at you. Or maybe they don't see emotional cheating the same way you do. Maybe they need lots of connection with a wide variety of people, whereas you don't.

There could be a lot of reasons, and these reasons could overlap and shift with time.

Strong attachments activate a web of old wounds and longings mingled with present-day desires and fears that influence how we try to defend against painful or overwhelming emotions within us, and/or against potentially uncomfortable experiences with an intimate partner.