A public proposal is a risky thing to attempt. For every couple whose love for each other is perfectly in tune, there is a partner who has woefully misjudged their lover’s desire for public attention, grand romantic gestures, or simply marriage full stop.

So Gabriel Grossman might have been taking a huge risk when he and his girlfriend, the Instagram influencer Marissa Casey Fuchs, embarked on not just a public proposal, but a 48-hour-long surprise holiday scavenger hunt, exhaustively documented by the couple on their respective Instagram accounts. What if she’d said no? Or decided that this precious moment was too personal to be shared with her audience of 193,000 people?

But perhaps Grossman didn’t need to worry. Not just because Fuchs has been sharing nearly every detail of her life for years and shows no sign of stopping – but also because it may not have been as much of a surprise as her audience were led to believe.

Before the “surprise” trip even began, marketers across New York had received a detailed itinerary of what it would contain. Spread over multiple pages, the PDF slide-deck detailed where Grossman and Fuchs would be, down to the hour, as well as what and how Fuchs would share on her Instagram account, from a “specialty shot” at the Surf Lodge at 9pm on Tuesday to a “Short Film Next Stop Post” at Gurney’s Resort at 8am the next morning.

The document promised to “capture heartwarming moments and surprise and delight the soon-to-be bride at every twist turn and flight!” It ended with an offer to brands of “the opportunity to align with this momentous occasion and the beautiful cities she will be visiting along the way”.

The slide deck was leaked to the Atlantic’s Taylor Lorenz, the Bob Woodward of the influencer world, who published it on Thursday. “The pdf not only is expertly designed, but also directly solicits brand partnerships and was sent to marketers under the guise of a possible sponsorship,” Lorenz wrote, dismissing initial claims from a friend of Fuchs that the document was a simple “logistical plan”.

Not that such a pitch would be likely to be particularly successful, says Arron Shepherd, co-founder of influencer marketing agency Goat. “I would find it very strange. It’s not something that’s coming along regularly. People will certainly tell us, “I’m going to be here at this time” and seek sponsorship, but something so personal as that … It’ll be giving birth next.”

Indeed, Shepherd worries that the pitch could end up doing more harm than good for Fuchs’ burgeoning celebrity. “The people that will suffer the most will be the influencers, not the brands. Influencers have very specific audiences, who are sensitive to betrayal.”

What influencers are selling, says Tom Winbow, UK MD of Ralph Creative, is authenticity, and when that is harmed, it can damage their business. “The strength of an influencer’s influence is really defined by the relationship with their audience. We find that those influencers who remain authentic and cultivate a real relationship with their audience are the ones who can genuinely influence their audience in to taking an actual action (and not just an empty like or comment).

“Social media was supposed to be all about authenticity and real moments, without the gloss of traditional media. Across all media, traditional and social, the trusted bond between author and audience is becoming more and more fractured. And stories like these only serve to damage this relationship further, meaning we should always ask ourselves, ‘What is real?’”

When the mask slips too much, the results can be actively unpleasant. Last year, fashion blogger Scarlett Dixon posted an Instagram shot of herself supposedly having breakfast. The picture, a sponsored post for a brand of mouthwash, was ludicrously over the top in its twee perfection, with Dixon, who Instagrams as @scarlettlondon, sitting on a freshly made bed, surrounded by pancakes and strawberries with an apparently empty cup of tea and pink heart-shaped balloons floating above her head.

As the image spread across other social networks, Dixon faced a torrent of abuse. “Each time I refresh my page, hundreds of new nasty messages pour on to my Instagram, Twitter and YouTube, some of which have contained malicious death threats,” she wrote in a follow-up Instagram post. “There are now hundreds of thousands of tweets circling the internet, shaming me.”

“My feed isn’t a place of reality,” Dixon added. “I mean, who spends their time in such a beautiful city, perched on a ledge, ice-cream in hand and smile permanently affixed to her face? It’s staged, guys.”

For the Fuchs/Grossman household, at least, the preparation didn’t seem to pay off. He told Lorenz that “most brands didn’t even respond”, with the bulk of the sponsorship coming from companies the pair already had dealings with. “I can be public for a bit for this one moment in our lives, then it will go back to normal.”