The bride-to-be shouldn't feel ashamed of her dad, writes Allison Pearson of the Daily Telegraph.
In 2011, when Michael Middleton was getting ready to walk his daughter down the aisle of Westminster Abbey, the 60-year-old businessman rehearsed his steps over and over.
Such was his dread of letting his beloved Kate down in front of an estimated TV audience of two billion.
"Thank goodness that's over and I'll never have to do it again," said Mike, returning with deep gratitude to the safety of his lawnmower.
Although the Middletons had to endure snobbish scorn for having been airline personnel, Kate's father was at least familiar with the conventions of upper-middle class life.
He had worn morning dress, he knew the hymns and adored his new son-in-law.
Compare and contrast the sad plight of Thomas Markle.
Meghan's father is a hard-up recluse, who lives in a run-down Mexican resort.
A bear of a man, he has a pendulous belly and walks with a defeated lope.
The poor guy probably thinks morning dress is T-shirt and boxer shorts.
At his own wedding to an enchantingly pretty Doria Ragland in 1979, at Hollywood's Self-Realization Fellowship Temple (yes, really), the then TV lighting director wore an orange shirt under an ill-fitting grey sports jacket. It was a long way from St George's Chapel, Windsor.
How daunting it must be for such an individual to be parachuted into a fearsomely grand wedding ceremony where he knows none of the guests (his daughter having not invited any of his relatives), and with zero preparation for the alien clothing and culture.
We know Tom Markle has spoken to Prince Harry on the phone (when the prince asked for his daughter's hand).
Otherwise, to the public, it seems as if this ailing 73-year-old was left to pretty much fend for himself in the full glare of media prurience.
Kensington Palace reported that Meghan wanted both her parents to be with her on this "happy and important day".
All that was thrown into doubt when it was revealed that Tom Markle had colluded with a British paparazzi photographer, who staged pictures of him being measured for a suit and staring at images of Harry and Meghan.
Although he says his motive wasn't money, Meghan's father is now damned as "grasping", "PR-hungry" and guilty of exploiting his royal connection.
For his part, he claimed to have suffered a heart attack (who can blame him?).
As a result, Tom Markle suddenly and shockingly pulled out of Saturday's ceremony.
I reckon this was down to one of four things:
a) He didn't wish to embarrass the royal family and his daughter.
b) He felt that his tarnished presence wasn't wanted.
c) His elder daughter, Meghan's poisonous, jealous half-sister Samantha, had convinced him not to go.
d) Like any normal person, he gets chest pains just thinking of a nightmare scenario where he has to take centre-stage and his son-in-law's grandma turns out to be the Queen.
It's been reported that Meghan pleaded with her father to change his mind.
As Prince Harry has a well-known hatred of the paparazzi, whom he blames for the death of his mother, you can see how things might have been a teensy bit tense at Wedding HQ.
Picture lovely Meghan, wailing: "This is a total disaster. I've given up my career, I'm holed up in here, I'm not allowed to talk to anybody, I can't trust anyone, I've fallen out with my family, my dad's not coming to my wedding. What the hell have I done?"
Honey, you're joining the Windsors.
As with everything in Britain, it boils down to class.
When a reporter broke the news of the impending nuptials to Ava Burrow, Meghan's lovely step-grandmother, she exclaimed: "Meghan marrying a prince? Who'd have thunk! I guess it's like your Downton Abbey - and we're the folks downstairs." Spot on, madam.
The Middletons managed to invite Uncle Gary, of "Maison de Bang Bang" fame, to William and Kate's wedding.
Partly because it was the right thing to do, and partly because black sheep can do a lot less harm when they're tethered to the seating plan.
By excluding her step-siblings, however disloyal and unsavoury, and her wider family, Meghan may have unwittingly put her father in a lonely position.
The tragedy is that dad and daughter have always enjoyed a special relationship.
From the day of her birth, friends recall, Meghan was his princess.
It was Thomas who bought two sets of dolls for the little girl he called "Flower" or "Bud"; one was black, the other white, and he wrapped them and put them together under the Christmas tree, to represent Meghan's mixed heritage.
It was Thomas who became unpaid technical director for every school production his daughter was involved in, teaching her the best poses and angles; Thomas who paid for her schooling and was main carer for much of her childhood.
When her dad's name appeared in the credits at the end of a programme, Meghan would run up and kiss the TV.
To not have her father walk her down the aisle on such a historic day, may well be one of those mistakes people look back on when marriages start to unravel.
All this could have been so easily avoided.
Why wasn't be brought over well in advance, set up in a comfortable hotel, taken to Savile Row and kitted out, and generally put as much at ease as possible?
Why, less than 10 days before the wedding, was he still in Mexico, no doubt feeling daunted and anxious and prey to paparazzi schemes?
Meghan should not feel ashamed of her dad.
Furthermore, she should tell him that no one is judging him for a single error of judgment, least of all the British people who only have sympathy for the poor bloke.
Besides, the family Ms Markle is marrying into has its fair share of chancers and fools.
It was when Lady Diana Spencer had her confidence knocked by a censorious institution that the rot set in.
God forbid that history should repeat itself.
When the sixth in line to the throne first clapped eyes on Ms Meghan Markle, he deduced, correctly, "I've got to up my game".
Those who climb from downstairs upstairs deserve more credit than those who arrive there by birth, not less. That is one lesson of this modern marriage.
We still don't know for sure that Mr Markle will make it to the church on time.
But there's always Doria. If Ragland were to become the first woman and the first African-American to give away a daughter to a prince, well, who'd have thunk it?
This story originally appeared on the Daily Telegraph and is reproduced with permission.