Charlotte Urie, 20, was left shocked after her boyfriend confessed he was actually born a girl.
With his strong jawline and muscly torso, Charlotte had no clue that the new man in her life - Kieran Moloney - had come into this world as a female called Ciara.
For years, the 23-year-old kept his sex-swap a secret, until he met Charlotte in 2012.
The couple have now been together for two years and are hoping to marry and start a family using Kieran's best friend as a sperm donor.
Charlotte, a barista from Camden, London, said: 'I would never have guessed Kieran's secret, but as soon as he told me he'd been born a girl it didn't matter to me.
'I was surprised, but I love him for who he is and see him as a man.
'He's very masculine and has a great body, but he's also my best friend.
'I never had any concerns about dating someone transgender. Biology doesn't matter.'
Kieran, originally from New Zealand, but now living in London, said: 'When I first met Charlotte, I was blown away by her beauty, but I was terrified of how she'd react if she found out I used to be a girl.
'I needed to know I could trust her, before I revealed my secret.
'Other girlfriends have been ashamed of who I am, but when I told Charlotte, she was so accepting. She's amazing.'
Kieran is yet to have full gender reassignment surgery, but the couple say Kieran's physical gender doesn't get in the way of them enjoying a healthy sex life.
He says: 'We've reached the stage where we feel comfortable enough with each other to do whatever feels good - that's what sex is.'
Kieran has been living as a man for seven years and after having a double mastectomy at 20, he finally feels comfortable in his own skin.
Kieran, who also works as a Barista, had been unhappy with his gender since he was four years old.
He had no interest in girly things and cried if his Mum put him in a dress and when he started primary school, he became a target for bullies.
He said: 'Kids didn't understand why I was different. I had no friends and I changed schools five times.
'The only time I was happy was when people mistook me for a boy.'
When puberty hit, the teenager's confusing feelings just escalated further.
He says: 'I hated seeing my breasts develop and I was jealous of the boys at school when their voices dropped and they started shaving. I hated being a girl.'
At 14, Kieran lost his virginity to a boy, but says it felt wrong.
He cut his hair into a short spiky bob and wore sports bras and baggy tops to hide his feminine figure.
After seeing a counselor aged 16, Kieran was finally diagnosed as transgender.
He said: 'I started taking hormone tablets which lowered my voice and gave me more body hair - I loved the changes.'
Kieran's family supported him and his mother Bronagh Moloney, 49, a nurse, began calling him her son.
By 17, fine hairs started to grow on Kieran's face and with a rigorous gym workout, Kieran's body was transforming into a man's.
He began binding his breasts with sports tape, spending £20 a week in his quest to hide any hint of being a woman.
Gradually, his cup size dropped from a B to an A.
In November 2009, aged 18, Kieran started monthly testosterone injections and, two years later, had a £5,000 double mastectomy that was paid for by his mum.
He said: 'When I saw the results I felt euphoric. I finally had a man's upper body, something I'd only dreamed about.'
In August 2012, Kieran changed his name by deed poll and met girlfriend, Charlotte.
Charlotte says: 'We both loved the same music and were into keeping fit.
'He's a man's man and loves football and going to the pub.'
The couple started dating and a month later Kieran confessed how he had been born a girl and was transgender.
Charlotte says: 'Kieran sat me down and said he had something to tell me. He then blurted out that he'd been born a girl called Ciara.
'I was so surprised. He was so manly. I never had any suspicions.
'Kieran was really nervous and told me he'd understand if I just wanted to be friends.
'We talked it through for hours.
'I knew I still loved him and wanted to be with him. It didn't matter he'd been born a girl.'
Kieran added: 'So many girlfriends before had been embarrassed by me and I didn't want any more rejection.
'I felt such a connection to Charlotte and I didn't want her to end the relationship, so when she reacted like it was nothing, I felt so relieved.