"By the end of that journey I was such an advocate for it as a concept that I thought I'd better do it myself," she says. "It felt like an obvious step, and all of my friends and family had become really into it, so by the time I said I wanted my own wedding, they were on board."
The nuptials were both holy and wholly unique; the vows Tanner wrote were all adapted from their Biblical origins, she wore a £60 vintage white dress and her father Malcolm, a 69-year-old painter and decorator, gave her away - to herself.
Afterwards, the 50-strong wedding party danced through the streets of Brighton and down to the beach to the sounds of Kendrick Lamar's I Love Myself playing from a boom box.
Generation Selfie's narcissism?
It's tempting to dismiss this as the height of Generation Selfie's narcissism, particularly as the ceremony is not legally recognised (Tanner's letter of enquiry on the matter to Brighton and Hove register office met with the response that marriage is "exclusive" to two people). But for Tanner, the weight of the occasion - a celebration of being single, and thoroughly enjoying it - still holds.
Initially, I thought of the wedding as a light-hearted thing, and held it during the Brighton Fringe so passersby could be a part of it", she explains. "But I got really nervous the day before: it felt like a really important thing to be doing, especially as it was one of the first [sologamous marriages] many people had seen. A few people told me it was the best wedding they'd ever been to. The atmosphere was amazing and it felt really powerful."
Though solo ceremonies such as Tanner's are unlikely to ever unseat the traditional union for two, they do seem to be on the rise; part of a much bigger social trend for women rejecting the traditional timeline of their mothers and grandmothers, and forging an independent path, worlds away from the 'spinster' stereotype.
I think it's hard not to adopt whatever society's messages are ... and I certainly think that one of the messages is, 'You are not enough if you are not with someone else,'
Erika Anderson said of her decision to self-marry. The 37-year-old, who lives in New York, wed her university sweetheart in her twenties but the pair split aged 30 after growing apart. Committing to herself, she said, was "an act of defiance."
The notion of marrying oneself entered popular consciousness in a 2003 episode of Sex and the City in which Carrie Bradshaw, its protagonist, announced she was fed up with forking out to celebrate friends' life choices, but never her own.
In 2010, one of the lead characters on TV musical comedy Glee enjoyed a solitary wedding ceremony. Now, with some 42 per cent of British marriages ending in divorce (unmarried women having outnumbered their married counterparts for the past decade), marrying yourself is, perhaps, the only safe bet.
Its proponents say that it is a modern rite of passage: "A wedding is just a marker in life," explains Alexandra Gill, a Canadian food critic who married herself in 2006 and renewed her vows on her 10th wedding anniversary last year. "Our mothers and grandmothers didn't have the choice to remain single... Self-marriage is an opportunity to celebrate our personal independence, self-reliance and freedom from the chains of convention."
Cashing in on sologamy
Unsurprisingly, a number of businesses have spotted opportunities in the popularity of weddings-for-one. Gill launched Marry Yourself Vancouver, a wedding planning and consultation service, last year; in Japan, where one in seven women are unmarried, Cerca Travel offers a two-day package that provides a dress fitting, make-up and hair styling and a photo shoot for upwards of £2,500.
Are these companies helping to de-stigmatise lone declarations of love or, as one website posited in response to Anderson's big day, "just looking to make bucks [off] a few sad feminists"?
"This is not a substitute for a partner, on the contrary it is [about being] a stronger member of society [and] more grounded as a person," says California-based jeweller Jeffrey Levin, who created a self-marriage kit service, I Married Me, despite being conventionally married to his wife, Bonnie.
The pair have sold "hundreds" of packages, which can include white gold wedding rings, vows and ceremony instructions for around £200, in a bid to "allow individuals to be have a physical, tangible way of self-reinforcement and positivity."
Of course, not everyone looks at the trend quite so positively. When news of Tanner's wedding hit the headlines a couple of years ago, many on social media were quick to call her a narcissist; acquaintances, too, haven't held back.
Men's reactions
"A couple of guys have become a bit incensed," she says. She has continued to date since her wedding ceremony, but has no plans to marry anyone (else). "One told me I couldn't have my cake and eat it by marrying myself and then going on to have other relationships, and a man I was having a holiday fling with flipped out.
I was surprised by the anger - it's not harming anyone. Most of the guys I've been out with have been really supportive. It's been a good filter to see their reactions when I tell them, as if they suddenly become wary, they're not the one for me anyway."
Tanner has one sister from her parents' marriage and four step-sisters from her father's second, ranging in age from 22 to 38; she is, thus far, the only one out of the six of them to have been a bride.
"We're all familiar with the fact that 2.4 children don't always work out," she says. "I think Mum might quite like me to find a nice man and be happy, but she knows from experience that things don't always end up like that."
What's the point?
If marrying oneself doesn't preclude having a relationships with anyone else, however, and confers no legal benefits, what is the point?
"You can be more lonely in a relationship that's not functioning than just being on your own, and a lot of people don't realise that," Tanner explains. "I hope seeing how empowering committing to yourself is, can liberate people and teach them that seeking solitude is a good thing. You can waste your life waiting for the one, when you are the one yourself."
Perhaps sologamy is simply the inevitable next step for millenials, who have already traded the traditional "grown-up" signifiers of home ownership and settling down for travelling around the world, itinerant careers and moving from one rented flat to the next. In these very modern marriages - as in so much else - the only constant appears to be themselves.
