Is your partner about to run off with your best friend?

No betrayal is easy to deal with but there’s one that delivers a near fatal blow – when your partner runs off with a close or best friend.

Losing your partner and the person whose shoulder you’d have sobbed on, is a double dose that’s particularly poisonous.

Research shows people who manage to survive and move on have one thing in common: they suspected something dodgy was going on, even if they didn’t voice their fears or both parties denied it.

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Knowing you’d recognise the signs if it happened again gives most of us the faith and confidence to love again.

Worried you’re in the middle of a love triangle?

Here’s how to spot it.

If you’re worried it could be about to happen.

Imagine your partner sat between you and the friend you suspect. If something fishy is afoot, he’ll sit close to you, but his body and gaze will turn toward her.

She’ll angle her body toward him, usually with legs crossed in his direction, and lean forward with her upper body.

She may rest her hand at the base of her throat, fingers splayed. Often, subconsciously, you’ll pick up an unwelcome vibe and lean in closer to him and your friend, to involve yourself in the conversation and establish your connection to both.

If you haven’t done it consciously, do it now.

Smile lots at your friend, make direct eye contact and throw a quick but genuine compliment her way.

Then make a subtle ownership gesture to your boyfriend, like kiss him on the cheek while simultaneously squeezing his hand or leg. This reaffirms your relationship to both of them, pushing the guilt button so hard, it can’t help but hit home how underhand what it is they’re contemplating.

If you think it could have been going on for a while

Watch for all the typical courting gestures because all will be evident, if done in secret.

She’ll briefly touch his leg under the table while you’re not looking, shoot loaded looks and make meaningful eye contact whenever you look away.

To catch them at it, turn your head so they can’t see your eyes (and appear to be looking in another direction) but you can still see them. Pretend to be absorbed in a task and watch for signs.

Betrayal relationships are often fuelled by lust (anything forbidden becomes appealing) so you’ll see lots of autoerotic touching (both of them will start caressing their own lips, necks, arms whenever together) and preening (smoothing or adjusting clothing or hair to make sure they look their best).

Watch for brief but sexy, wry, intimate smiles and pay particular attention if the conversation turns to sex or relationships.

The guilty will react one of two ways: clam up and look intensely uncomfortable or they’ll play flirty little games with each other (and you).

If she’s single, she might say ‘Sex? What’s that! It feels like I haven’t had sex for a million years but God, I’d just love to do it right now.’ This will be followed up by a quick look at him from under her lashes. If she’s attached, she may be over-attentive to her partner and over-flirt with them instead.

Another classic move is to kiss their partner, while maintaining eye contact over their shoulder with the person they’d like to be snogging.

The potential lover gets to see what they’re like in action - or recall their last kiss.

It effectively says I wish I was kissing you.

Your friend fancies your partner but isn’t acting on it.

People react different ways to fancying someone they shouldn’t.

Take notice if friends who appeared to adore your partner suddenly aren’t as friendly.

If your best friend Hugh has gone weirdly quiet around your girlfriend Emma, it’s often because he knows something you don’t (your girlfriend’s playing around generally) or he fancies her himself.

If we fancy someone we shouldn’t, we sometimes tend to become less ‘matey’. We’re scared we’ll give too much away if we’re chummy, so we create distance.

Along with the new aloofness can come slightly aggressive teasing. He’s resentful he can’t have her, so he’ll subconsciously seek to decrease her ‘value’ to him by belittling her.

Sometimes people are so successful at doing this, they not only cease to find the forbidden person attractive, they’ll start to wonder why their friend still does, dropping ‘You could do better’ hints.

Your partner’s not interested in their advances.

If they seem slightly embarrassed whenever the person is around, fixing you with desperate, devoted looks.

They’re trying to transmit a message with their eyes: ‘I want you to realise he/she’s hitting on me and I don’t like it but don’t want to hurt you by telling you because this person is your friend’.

They’ll also close themselves off from the person: turn their body away from them and toward you, refuse to make eye contact and avoid being near them in situations where there’s close body contact (like sitting next to her in a crowded car).

Your partner is interested.

It’s bad news if, instead, they start mirroring the person’s behaviour. Are they standing the same? Talking on the same volume level? Do they drag on their cigarettes or sip on their drinks at the same time? If so, they’re bonding on a subliminal level.

Which way are their feet and hands pointing? Even if his torso faces toward you, a foot pointed squarely and firmly one pace in her direction may be a sign he’s attracted.

Test you’re right by doing the following: Move closer to your partner, mirror their movements, smile warmly at them, drop your voice to a low intimate level to talk about something which clearly links you ("What are we doing this weekend, darling?") and push an imaginary hair out of their eyes.

All are ownership gestures which say ‘Back-off!’ but it’s your partner’s reaction which is important.

If they resist you: go stiff and move or lean backward when you snuggle in, refuse to be involved in an intimate discussion and turn their body away from you when talking to the ‘suspect’, the writing’s on the wall.

Also, watch their eyes.

Sometimes, they’ll lean in with their head to listen while you’re whispering in their ear but keep their eyes fixed on the other person. It’s the equivalent to the snogging scenario: I wish it was you, not my partner, whispering in my ear!

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