Katie Lucia Keegan tweeted on Saturday night that she was "so proud" of Ryan following his performance of 'No Name' on BGT, which he revealed was about a friend he'd love for years.
The 19-year-old also tweeted a picture of an appeal to find the mystery girl, saying: "woooooo its me #lolololol". She added a shot of a paper's front page of her and Ryan, admitting it was very flattering.
[Related article: Britain's Got Talent: Ryan O'Shaughnessy's No Name melts hearts]
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In January, Katie shared a picture of her and Ryan in their formal wear, with the caption: "just remember....... I was there.... when no one else would go."
It sounds like this was the moment Ryan knew his feelings were more than just friendly, as he revealed seeing her in that dress made him realise how beautiful she was. They first became friends at Dublin's Portmarnock Community College six years ago.
Ryan O'Shaughnessy's song impressed judges Simon Cowell, David Walliams and Alesha Dixon.
David Walliams called it the most beautiful song he'd ever heard, and said he couldn't believe she wouldn't go out with him, while Alesha Dixon said it was sweet and sincere.
Simon Cowell tried really hard to get Ryan to reveal the girl's name, but he resisted.
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Ryan O'Shaughnessy has opened up about Katie now, telling the Sun they've spoken on the phone and Katie is flattered and loving it. However, he added: "I don't think she realises I'm in love with her yet."
Erm we think she does, Ryan.
He admitted that he gets nervous around her and doesn't want to rush into anything with his fried. Ryan did have plenty of praise for Katie, saying: "she's a nice girl and has a beautiful smile."
The 19-year-old from Dublin has already got plans for the £500,000 prize money if he wins, revealing he'd spend it on a holiday for him and Katie, and "maybe a sparkly ring if she's lucky."
We'll watch this space.