She politely declined.
“Maybe it was his accent,” she laughed. But he persisted.
That was almost three years ago, and what a time it has been for this young couple.
By the time they met, Summerhill native Keoghan had already exploded onto the Irish acting scene as the infamous cat killer in "Love/Hate".
The 26-year-old has since wowed audiences in Dunkirk, The Lobster, American Animals, and was surrounded by Oscar rumours for his incredible turn in The Killing of a Sacred Deer.
More recently, Keoghan landed a key role in the next chapter of the Marvel Cinematic Universe.
After Marvel wrapped its Avengers storyline with this year's Endgame, they announced a number of comic-inspired films which will be released over the coming years; including The Eternals, starring Angelina Jolie.
Last month, Keoghan – also a Dior brand ambassador – was announced as one of the cast members of the film, including Gemma Chan and Salma Hayek.
So what is it like when date nights are bombarded with adoring fans and texts from the likes of Colin Farrell?
For Guerin, it’s the icing on the cake after seeing her boyfriend's “hard work pay off”.
“I enjoy it, it’s a crazy buzz and it’s also very weird! The premieres I've been to have been exceptionally big with huge stars so I’ve been overwhelmed but in the best way, like I constantly find myself pinching my arm just to make sure this is all real,” she said.
“But I feel so grateful and lucky I get to support Barry because I really can’t stress enough that no one deserves it more. That boy puts his heart and soul into his work and he has the biggest heart. He cares for everyone around him so much,” she added.
The 23-year-old compared her approach to preparing an outfit for these star-studded events to her own school debs.
“I didn’t think about the debs until two weeks or even the week before and then panicked and freaked out until I found something and it’s the very same with premiers,” she laughed. “I try to be a girly-girl but I think I’m more of a tomboy which my dad can take the credit for,” she said.
She recalled the figure-hugging scarlet red dress that she wore to her first premiere, at Leicester Square nonetheless, as her favourite look thus far.
“I definitely have been my own worst critic when it comes to seeing press pictures, and social media has played a big part in that, unfortunately. It really can get into your head and affect you in the worst way,” she noted poignantly.
“Thankfully I have great family and friends, my mom is one of the best listeners I have, I’m very lucky we’re so close. But it’s made me take a step back and I’m honestly just trying to give myself a break and remember it’s ok to not look like a Victoria Secret model all the time,” she said.
Guerin is also taking a breather from the pressure of college and feeling the need to be 100% sure about what kind of career she wants to pursue.
“It’s taken me some time to realise that it’s ok to not have everything mapped out. I’m actually enjoying the unknown at the moment and I’m also working on raising awareness for the housing crisis and the drug addiction epidemic in Ireland with Barry,” she said.
While spending time figuring out what's next on the agenda, Guerin has also been delving into photography.
While Keoghan busies himself on set, the Kerry native is slowly learning how to pluck up the courage to ask strangers if she can take their portraits.
“Of course it’s hard not having a specific title when someone asks [what I do] - but I’m lucky enough to go away travelling with Barry and we’re young and happy. I’m just doing things that will make me happy and I’m sure the rest will follow soon,” she said.
The loved-up couple is currently residing in Los Angeles for the summer, as Keoghan steps into the glittering role of A-lister.
For Guerin, LA is a world away from the hectic New York lifestyle they battled with last summer.
“There’s so many different characters, you don’t meet the same person twice. It’s definitely been a big adjustment and I remember the first week we came over I rang my mom because I just couldn’t get over the vast amount of people, I felt like an ant! I’m lucky I have Barry because he’s a city kid and has his wits about him - he’s definitely got more street smarts than me,” she joked.
While they may seem like two of the many young 20-something Irish who made the Big Apple their home, their recent highlight reel looks a little different.
Red carpets, films sets and they even managed spent time with Canadian rapper Drake backstage at his Madison Square Concert (“That was insane,” Guerin agreed!)
She noted that getting to explore the metropolis with someone “equally as quirky” as she is the experience of a lifetime.
“We like going to places where we’ll find characters and just take the atmosphere in, laughing like kids at the stupid little things - we think we’re comedians but really we’re the only people laughing at ourselves,” she said.
The Eternals is due for release in November, 2020.
Main image by @shona_guerin