WANDER WOMEN COLLECTIVE via Getty Images Man texting SMS on mobile phone in bed

So, I'm just wondering... whatever happened to trusting one's own gut? Is it unfashionable to do so? Politically incorrect? Fattening? There must be a reason that so many people have stopped doing it.

As a couple's mediator who works with couples trying to overcome infidelity and broken trust, I hear this kind of thing all the time:

"My husband is constantly texting a female co-worker. He says they're just friends, but he guards his phone like it carries state secrets and leaves the room to text her. When I tell him it bothers me, he says I'm controlling and accuses me of not wanting him to have any friends. Now he's locked his phone and won't give me the password. He says I'm paranoid and it's my problem."

Or this:

"My wife has struck up a friendship with a man from her gym. They're constantly texting back and forth and sending workout pictures of themselves. She says I'm insecure and they're just friends, but yet she instantly deletes her text message history after they've texted. If I ask to read their texts, she says that I don't respect her privacy."

Look, I strive to be unbiased, but there comes a point when behaviour becomes conspicuously shady. And the dialogues above would seem to fit onto that shelf.

Yet you might be surprised how many people don't -- or won't -- trust their gut and accept the strong possibility that their spouse and their texting buddy are more than "just friends." Or maybe it isn't really about trusting one's gut. Maybe it's just about living in denial.

The truth is, many opposite-sex friendships are sustained because of a simmering attraction between two people.

Or maybe it's about falling for all the manipulations and insults that a committed person will use so that they can continue to indulge in a "friendship" that they know is inappropriate and disrespectful to their primary relationship.

The truth is, many opposite-sex friendships are sustained because of a simmering attraction between two people. If circumstances were different, they could easily be sexual partners. And they know it. This underlying current of attraction makes talking, texting and spending time together as "just friends" all the more exciting. It has an erotic edge to it.

Of course, it's only a matter of time until a person's spouse begins to notice this increasingly intimate friendship and get worried. They may ask "Who are you texting?" or "Why are you texting so-and-so all the time?" or they may say, "It bothers me that you're texting him/her all the time."

And that's when it starts. The defensiveness, downplaying and deflections. The insults and indignation. Too often, a committed person who knows that an extra-marital friendship is inappropriate will deny, deny, deny that it is. Instead of respecting their partner's feelings and addressing their concerns, instead of quickly and clearly putting their primary relationship first, they'll do everything they can to ensure their "friendship" continues.

Unfortunately, this often involves turning the tables so that their partner's behaviour looks problematic, not their own. To do this, they may employ any number of "drop it" tactics.

This person will act like their human rights are being violated when their spouse asks them to distance themselves from their opposite-sex "friend." "It isn't fair! I didn't do anything wrong!" Or they'll put on a show of feigned bafflement: "Why are you worried about this? I'm married to you, what does it matter what she/he texts me?"

Any professional who works with couples will tell you that the vast majority of affairs begin as opposite-sex friendships.

They'll cruelly dismiss their partner's concerns: "There's nothing going on, it's all in your head. You're paranoid." Or they'll come up with all kinds of rationalizations and excuses: "So-and-so sends flirtatious texts to everybody, that's just the way she/he is. I can't control what she/ he sends me."

Another tactic is to basically shame their partner into silence. We all know how public shaming is used nowadays: it allows the shamer to assume a position of moral superiority and simultaneously bully or embarrass another person into withdrawing, usually via a combination of name-calling, humiliation and distortion. Well, this happens in intimate relationships, too. "You should see someone about how controlling and jealous you are. You're turning into the typical insecure wife/husband."

Ouch, right? Right. That's why this tactic works. Nobody wants to be "that wife" or "that husband."

Now all of this begs the question: might the suspicious partner in fact be jealous and controlling? Sure, it's definitely possible. Some people are like that. That's why I always encourage my clients to start by self-checking their own behaviour. Are you the problem? Is your partner so sick of your suspicions or accusations that they're finally taking a stand and locking their phone? Because that happens.

Yet more often, I see that pendulum swing to the other extreme. I see spouses who harbor deep feelings of suspicion, sadness and worry with regard to their spouse's opposite-sex "friend," but who nonetheless bite their tongue instead of voicing those suspicions. That's because those "drop it" tactics work so well.

Nonetheless, you may need to be "that wife" or "that husband." You may need to put less stock into what someone else is telling you -- "We're just friends!" -- and more stock into what your gut is telling you. "Something isn't right here."

The more time, energy and affection your partner is spending on another person, the less they're spending on you. So protect your marriage. Protect yourself. Trust your gut.

Any professional who works with couples will tell you that the vast majority of affairs begin as opposite-sex friendships, especially of the type enabled by personal technology such as texting and social media. These can create a false sense of intimacy that can fast-track a "friendship" into something more.

If your partner says, "We're just friends" but guards or locks their phone, deletes their text history, goes into another room to text, and/or receives flirtatious or excessive texts from an opposite-sex friend whom you suspect of being more, you likely have cause for concern. If your partner dismisses your concerns or disregards the impact the extramarital friendship is having on your relationship, then it's safe to say there's a problem that needs to be addressed.

There's a lot you can do to regain control (in a good way!) of your life and marriage. If you've respectfully asked your partner to limit the extramarital friendship and he/she has refused, you may need to get some outside help. The longer these "friendships" go on, the more entrenched they get and the more defensive people get of them. I should know, since this issue is a common one I see in practice.

But step one is to get your own head around it. Instead of feeling insecure or ashamed to insist that your partner limit or end an opposite-sex friendship that is causing a rift between the two of you, have confidence in your own assessment of the situation and in your own ideals of what is appropriate within a marriage. Marriages can be fragile things. The more time, energy and affection your partner is spending on another person, the less they're spending on you. So protect your marriage. Protect yourself. Trust your gut.