One of the cruellest things about relationship trouble is that it's often invisible to the people inside it - but painfully obvious to everyone else.

Friends exchange looks. Family tread carefully. Meanwhile, you're busy explaining it away: 'We're just tired.' 'It's a phase.' 'Every couple goes through this.'

They do.

But some 'phases' are warning signs – and when you're emotionally invested, your brain becomes good at minimising, normalising and rationalising things you'd instantly flag in someone else's relationship.

These are the warning signs others see first – the blind spots that are hard to see when you're in the thick of it.

Tracey Cox reveals the five warning signs in your relationship all your friends and family are secretly talking about and you're oblivious to

You're keeping a relationship scorecard 

What your friends see: 'Every time we go out, one of them brings up something the other did to them years ago. It's like they keep a tally of who did what when to see who's winning. Nothing is ever forgiven or forgotten about. If we say anything, their answer is always that they're playing around. But there's nothing playful about it.'

What's going on: In healthy relationships, couples talk about the good times and remind each other of the nice things they've done to make the other happy. This sets up a cycle of positive reinforcement: Aren't we wonderful together and to each other!

Keeping score of wrongdoings is an excellent way of making sure that pile of guilt and bitterness from the past never disappears. It's never harmless fun. Not for you and not for the friends who cringe with embarrassment every time you do it.

Stop it: If you're still talking about something that happened years ago, you haven't dealt with the issue. Talk honestly about why it hurt you so much and make a new pact to only bring up good things from the past.

You roll your eyes behind each other's back 

What your friends see: 'My friend insisted all was well, but I noticed that every time her husband made a joke, she'd catch my eye and roll her eyes. It said, "See what I have to put up with? He's an idiot". They split six months later.'

Some 'phases' like rolling your eyes and being jealous are warning signs for deeper problems in the relationship (stock image)

What's going on: It might seem trivial but constantly rolling your eyes is one of the most damaging things you can do in a relationship.

World-famous researchers, John and Julie Gottman, studied thousands of couples over several decades to identify four behaviours that predict divorce – and were right around 94 per cent of the time.

Of all the four behaviours – the other three being criticism, being defensive and stonewalling (refusing to talk or engage) – contempt was the strongest predictor of divorce.