So many women are being blindsided by appalling partners 'doing a Jon Hamm'. It's happened to me FIVE times... but now I've realized my mistake: JANA HOCKING

There are few dating humiliations more brutal than giving a man the best years of your life while he insists marriage is 'just a piece of paper' and children aren't for him, only to watch him put a ring on the next woman's finger and get her pregnant before you've finished paying off the holiday you took together.

It is such a common male phenomenon that it deserves its own name. From now on, we're calling it 'doing a Jon Hamm.'

Why?

Because this week, the 55-year-old actor revealed he is expecting his first child with wife Anna Osceola, 38, after famously spending 18 years with actress Jennifer Westfeldt insisting he didn't possess the 'marriage chip' – yes, that's a real quote – and wasn't particularly interested in fatherhood.

How extraordinary. After nearly two decades of treating marriage and babies like two highly contagious diseases, he miraculously recovered in the arms of another, younger woman.

Now, I've been very vocal about not wanting children, but marriage? Oh yes. I want the commitment in writing, preferably at Manhattan's City Hall, followed by martinis, fries and oysters at Balthazar with our closest friends. Not that I've given it much thought.

So, believe me when I say I know the heartbreak of being the foster girlfriend all too well.

I know what it's like to train these men well – taking them shopping for nice clothes, helping them pick out nice wines – only for them to leave you and skip down the aisle with someone else. The last five, yes, five, men I've dated have gone on to meet their 'one' right after me.

For a while, I genuinely thought I might be their lucky charm. Date me, and hey presto, you're well on your way to meeting your perfect match.

But there's a special type of heartbreak I've witnessed far too many friends experience, when they've been keeping one eye on their ticking fertility clock and another on a man who 'just wasn't ready yet' but somehow found himself remarkably ready with someone else.

Just last year, I had three girlfriends race to freeze their eggs after break-ups. Break-ups they weren't expecting, with men they were hoping would be their forever person.

And that's what's so cruel about 'doing a Jon Hamm': the man gets congratulated for growing up, while the woman who waited years for him to do it is left frantically googling egg-freezing clinics.

Take my friend *Sophie.

She spent eight years with a man who assured her he loved her and could see a future together, but whenever she tried to put an actual shape around that future, he became strangely philosophical.

Why did they need a wedding to prove their love? Why couldn't they simply enjoy what they had? Why was she putting so much pressure on an arbitrary timeline? Isn't it all just rubbish anyway?

This is a marvelous arrangement for a man who wants all the comforts of a wife while keeping the position technically vacant.

Sophie supported him through a career change when he decided law was 'boring' and he wanted to try his hand at opening a country pub. They moved across the state and invested all their (her) hard-earned savings into getting this pub back up and running. He somehow even got her dad to invest.

When she turned 34, she told him she wanted to start trying for a baby within the next year. He replied that he still wasn't sure he saw himself as a father. Not yet anyway.

After four years of waiting and having given up her interior design job to make this pub work, he accidentally tripped and fell on top of their head bartender, who then announced she was pregnant.

Ten months later they were engaged. Before Sophie had paid back the debt, it turns out they were heavily in, he had a ready built family.

With no savings, she moved back to the city and in with me. She cried her eyes out for far too long over a man who had chosen another life.

Sophie found out about their second pregnancy on Instagram while sitting in the waiting room of the fertility clinic where she had just paid thousands of dollars to freeze her eggs.

'I stared at the photo of him holding the ultrasound while I was holding a consent form warning me that freezing my eggs was no guarantee of a baby,' she told me. 'That was the moment I realized he had never been confused, he just hadn't chosen me.'

For months, she asked what did she have that I didn't? The answer may be nothing.

Often, the next woman simply arrives after the previous one has completed his emotional apprenticeship. She endured the beta-testing phase; someone else received the finished product.

Obviously, I hate that man.

Then there's my friend *Emily, who was 37 when her five-year relationship ended.

Her partner always said he wanted children 'one day,' but one day remained stubbornly absent from every calendar they shared.

First, he wanted to buy a home. Then he wanted to make partner at work. Then they had to get a dog 'to give it a practice run.' Then they needed to travel because, as he regularly reminded her, once you have children, your life is over.

Each milestone was supposed to unlock the next stage of their relationship. Instead, whenever they reached one, another appeared conveniently in the distance.

'I kept thinking if I could just get him over the next hurdle, he would finally feel secure enough,' she told me. 'I didn't realize he would always be able to invent another hurdle.'

There is a reason 'not yet' can keep a woman trapped far longer than 'no.'

A firm refusal gives her a decision to make, but a gaslighting 'Not yet' hands her hope, and hope can be a very expensive thing when it is being funded by a woman's reproductive years.

Emily finally left after he refused to discuss a timeline for children, telling her that the pressure she was putting on him was making him want them even less and, I quote, 'kind of a turn off.'

Nine months later, a mutual friend called to warn her that he was expecting a baby with the woman he had started dating shortly after their break-up.

'He had spent five years telling me we needed to be completely ready,' she said. 'Then he got someone pregnant before they had even celebrated an anniversary.'

Naturally, people will say that everyone is entitled to change their mind. Of course they are. But the person who paid for that lengthy voyage of self-discovery is entitled to feel furious about the fare.

A man who discovers at 55 that he would rather like to become a father is praised for his 'personal growth,' and yet a woman cannot assume she will be offered the same generous extension on her fertility.

We are not afforded that 'Peter Pan' never grow up experience. Because tick tock goes the fertility clock.

That is why this particular heartbreak cuts deeper than an ordinary break-up. You are grieving the years you spent taking his indecision seriously, only to discover how decisive he could become once you were out of the picture.

So, we turn his lack of enthusiasm into a complicated psychological puzzle. Perhaps his parents' divorce damaged him. Perhaps his career needs to be more secure. Perhaps, if we love him beautifully enough, he will finally feel safe. Perhaps he's just 'dismissive avoidant.'

The complicated explanation hurts less than the obvious one.

Sometimes 'I don't want to get married' means 'I don't want to marry you.'

Of course, the new woman is rarely the villain in this story. She may simply have met him at the precise moment he realized his indecisive little Peter Pan act was no longer charming. Or when he woke up one day and suddenly had his 'green light' epiphany we keep hearing about.

Or perhaps, by the time she arrived, he had learned that 'I'm not ready' eventually stops working.

Either way, women need to stop treating a man's reluctance as a challenge they can overcome through sufficient patience and a dazzling girlfriend performance.

If you want marriage and he tells you it is meaningless, believe him. Take him at his word. If you want children and he cannot tell you whether they feature in his future, don't donate your remaining fertile years to his decision-making process.

Because while you spent years waiting for him to become husband material, you were really training him for someone else. We're not doing that anymore.