There are five reasons why most relationships break down.

A lack of honesty and inability to be vulnerable with each other. Lying. Unequal terms of the relationship.

And most of all: Repeat offences

All of these actions can be coupled together in one fell swoop when we consider that lying about your age in a relationship is pretty much the worst lie you can tell.

I know I know – I can already hear half of you shouting me down – cheating is surely the worst!

Well, this is a different sort of situation, I think we'll all find. Cheating relies on a breach of implicit trust, some sort of fracture between the relationship that forces a person in a direction that they can't come back from.

There is action and consequence; cause and effect.

By contrast, with lying about one's age, there are so many reasons why it's a bad call.

First of all, there's no reason to! Before you've met the person, even if it's a blind date, you have no reason not to be yourself. You are meeting a person for the first time; why would your age come into it unless you were hiding something.

This willingness to lie at the onset of meeting a person is also worrying because it was unprompted and intended to deceive. Either to give an air of mystery or maturity by pretending to be older or, more problematically, by lying about being younger than you are.

This, again, falls into two categories

One – frankly, criminal…

I think we can figure where this is – it's obviously a dating deal breaker if someone is lying about their age and it figures into a relationship in which their real – concealed age – is illegal.

Essentially, if the relationship involving a minor – or, at any point during its' course, involved a minor – then no one should be lying about their age.

That's just an unchallengeable fact.

That said, the other half of the matter is lying about your age for reasons of vanity or aesthetic.

While it may seem less important or relevant – 'age is just a number yadda yaddah,' that's precisely the point.

There is no reason to lie about your age unless you stand to benefit, and then that further backs up the argument. If you are deceiving someone – not just once, accidentally, but from the start until the end, consciously, that's bad.

There are no two ways about it

This person knows exactly what they're doing, and frankly, there isn't any coming back from that discovery.

It is a total breach of trust, and ask yourself this:

If they're lying about that, they could be lying about everything and anything.

Unsettling, isn't it.

I wouldn't like my partner lying about being vegan, let alone entirely reinventing themselves for a relationship.

It also reveals that I have been having a very different understanding of the relationship than the other person. In lying, they have acquired all of the power, without me even knowing it.

It's much sneakier than you think – particularly when they get their parents or friends involved in the setup. No one should make you feel silly or club together to pull the wool over your eyes.

It's just plain wrong

If you don't understand that, you've not been listening.

Back when you told your friends 'I've discovered my perfect guy,' it's now time to confess: 'my perfect guy lied.' They will be there for you to pick up the pieces and put you back together again, don't worry.

It's also not your fault for not seeing the red flags; clearly he's a pro at lying.

I know it's romanticized to have a large age gap or for women always to be younger than the man. I understand that this is a powerful standard to hold people to.

However, that doesn't mean that people are ever justified for lying about their age in a relationship when the very minimum that is demanded should be honesty.

Also, if the person never intended to tell you the truth themselves, it means you had to snoop to find this out. That means you could have either been in danger or were otherwise feeling suspicious enough to check out their stuff.

Suddenly you know nothing about them: their college degree, their real life, where they lived…

It dissolves in an instance

Their past long-term relationship confessions or their promise to stop smoking can both be dismissed now. They established this culture of lying to impress and ensnare you.

He has played havoc on your mental health, and forced you to reflect on your whole history together, all the road trips and family holidays. Gone.

This goes beyond a white lie on a dating profile or a fib that they spent a summer in New York City to find common ground with you. This is unforgivable, and here's why.

I doubt we need to be a relationship expert to see that the writing is on the wall here.

My best dating advice? If he's lying about his age, send him on his tracks.

It's just not worth it.