It usually happens about two months in.
You're snuggled up after a great sex session and the thought pops into your head, uninvited, and lingers: How many times have they done this before?
The 'how many before me' question is undeniably interesting.
You're curious about other areas of your partner's life, why wouldn't you be curious about their sexual past?
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The question 'how many before me' is undeniably tempting and usually happens around two months in
But think twice before you actually ask this loaded question.
What will you gain by knowing the answer? In my opinion, very little.
Numbers mean nothing without knowing the circumstances
Knowing the amount of lovers your partner has had without knowing the age and stage they were at when it happened tells you very little.
Say they admit to 40 lovers.
They might have clocked up 38 of them between the age of 18 and 25 and had a modest two more in that last 20 years.
Or they might have had two lovers, then got married and had six affairs, topping up the total after being separated for just one year.
Or perhaps they added the last 20 at an erotic 'sex party' like Killing Kittens – oh, and those 20 happened to be same sex rather than heterosexual encounters.
To make sense of someone's final number, you need a lot of detail. Do you really want to know that much detail?
Knowing someone's sex number without the details is a bit like snooping, finding something out and not being able to ask for an explanation.
You drive yourself mad imagining who, what, where, how (and how good).
Unless your partner's prepared to answer one hell of a lot of very personal questions, knowing their number is going to accomplish little else but drive you nuts.
Less partners doesn't mean safer sex
Sexpert Tracey Cox explains why revealing your 'number' isn't always the best idea
If you're asking to calculate whether sex is going to be safe, it's not the number of sex partners you want to know, it's the amount of times your partner had unprotected sex.
The person who slept with 50 people and used a condom every single time is a safer sex bet than someone who's had sex with five people and never used protection.
And what about all the people they've slept with 'indirectly'?
If they're in the habit of not using condoms and you sleep with them unprotected, you're also exposing yourself to all the other partners your lover has had sex with – and all their partners.
During British Sexual Health Week last year, a UK pharmacy (Lloyd's) published an online sex calculator that computed the number of indirect partners we have based on the number and age of actual sex partners we've had.
A man who has slept with nine people (without condoms) has around 2.6 million (yes, million) indirect sexual partners.
If he was truly honest, that's the figure he'd be confessing to!
Everyone tailors their answer to who is doing the asking
'So how many people have you slept with?' If it's a group of old girlfriends asking the question, you're six bottles in and at that no-holding-back, slightly boasty stage, you're far more likely to be unflinchingly honest (and maybe even up the score a bit, if you're feeling competitive).
If the person asking is your new, sweet boyfriend who you're desperate to please and don't know the sexual history of, the answer will be very different.
People tailor their answer to fit what they think will be the most acceptable to the person doing the asking.
If most people lie, what's the point of asking?
What is 'sex' anyway?
Does sex mean intercourse? What about people you've had oral sex with or heavy petting sessions? Do they get added to the total?
Your partner could have had a hugely significant, intensely erotic sexual relationship with someone without ever having had penetrative sex with them.
Knowing the amount of lovers your partner has had without knowing the age and stage they were at when it happened tells you very little
Isn't that relationship more interesting than one awful, drunken one-night stand when sex was over in a nanosecond?
It's the stories around sexual relationships that tell us about the person who had them, not the amount of times their genitals have penetrated or been penetrated.
Men and woman answer differently
Yes, it's better than it was in the past but the old double standard is still kicking along out there with women continuing to be judged far more harshly than men.
Lots of younger women now argue women should be out and proud about the number of lovers we've had in a bid to stop 'slut-shaming' and adjust society's expectations to a more realistic number.
I applaud the sentiment but still believe the number of people anyone has slept with is their business – male or female.
If you want to share, fine.
Being forced to isn't fine, no matter how altruistic the reasoning.
There is no perfect number
Our upbringing, early sexual experiences, how judgmental our partners have been, whether we've cheated or been cheated on – a myriad of factors contribute to who we are sexually today.
Our past shapes us but being with someone new is the chance to wipe the slate clean again.
What matters is what your partner is going to do from now on, now they've met you.
What they did before you came along isn't really relevant.
Ask a different question to find out what you really want to know
What we're really asking when we ask the 'How many?' question is often 'How special am I? Do you behave like this with everyone?'.
Which, let's face it, is a much nicer question to be asked.
So if what you really want to know is 'Am I special?', ask that.
If what you really want to know is how safe they have been sexually in the past, ask that.
Or you could ask nothing and find out the significant sex and love relationships your partner has had over time, when they naturally occur in conversation and where you're both headed.
Isn't that a better plan?
