But the two women are actually a couple expecting their first child together — after Kirstie left her husband, Dave*, to be with Aimee.
Kirstie, who has three kids with Dave, says: “Nobody is more surprised than us at the way things turned out. I was a married woman and never planned to have an affair, least of all with another woman.
“But we’re both so happy and can’t wait for our son to be born.”
Both Kirstie and Aimee had always considered themselves strictly heterosexual until they were brought together by mutual tragedy.
Aimee, 27, registered with a Facebook support group after her daughter, Megan, was stillborn at 32 weeks in 2009. Kirstie, 30, had set up the group, called Born With Wings, after having a stillborn son.
Baby bump ... Aimee shows Kirstie's kids
Soon Aimee and Kirstie were chatting to each other online each day.
Kirstie lived with Dave, her husband of nine years, and their kids — now five, seven and nine — in Lowestoft, Suffolk. Aimee and her boyfriend Jeff were based hundreds of miles away in Liverpool.
But the new friends quickly formed a strong bond, as Aimee turned to Kirstie for comfort.
Aimee says: “Losing Megan devastated me. Jeff and I couldn’t wait for our daughter to arrive. When we lost her, our world collapsed.
“It pushed us apart. I wanted to talk about her but Jeff dealt with it by bringing down the shutters.”
Four months later, Aimee and Jeff split up. She says: “I’d gone from having everything to nothing. I sobbed at Megan’s grave every day.”
Inspired by Kirstie, Aimee decided to commemorate her daughter by setting up a charity, Megan’s World, which helps grieving parents pay for headstones.
Three months later, in June 2010, she was nominated for a local hero award and asked her new pal to accompany her to the ceremony. Aimee says: “I didn’t feel nervous when I met Kirstie. I felt I already knew her better than anyone else in my life.
Fresh start ... Aimee Watson and Kirstie Maguire with cot for their unborn son
“The next day Kirstie was due to go home to Dave but I asked if she could stay on to help me with my charity work.”
Kirstie agreed and they spent the day collecting items donated by local companies for a raffle.
But that night, as they sorted the prizes, everything changed.
Aimee says: “One minute I had a glass of wine in my hand and we were chatting and laughing, the next we were kissing. My heart was racing and I didn’t want to stop. We were both confused but we couldn’t ignore the attraction between us.”
Kirstie offered to stay another day “to help”. That evening the pair ended up in bed together.
Kirstie says: “Afterwards, we talked about how we felt. There was a sexual attraction but it went much deeper too.”
Guilt-ridden, Kirstie phoned Dave to confess but, amazingly, he dismissed it as a drunken one-off.
Even more surprisingly, he then agreed to let Aimee visit their home in Lowestoft the following week.
Aimee says: “I was nervous about seeing Dave but when I arrived he let me in and told me to go up and wake Kirstie. It was like he was offering me his wife on a plate.”
Aimee and Kirstie spent the weekend kissing whenever Dave’s back was turned. A few weeks later, Kirstie and her family repaid the visit at Aimee’s home in Liverpool.
Aimee says: “I think Dave came to make sure there was no funny business. But we still managed a kiss. I knew we couldn’t end it.”
But it was only when Aimee went on holiday with another friend that she realised she was in love.
Aimee says: “It was meant to be a typical girls’ holiday, clubbing and chatting up men but all I could think about was Kirstie.”
Back home, Aimee decided to move closer to her friend and set up a new branch of her charity in Lowestoft.
When Dave heard, he agreed to let Aimee move in with them while she looked for a flat.
Aimee says: “To the outside world Kirstie and me were just friends but when Dave was out we acted like a couple. I even spent Christmas with them. Dave played computer games while Kirstie and I cooked and played with the kids. It was bliss.”
But days later, a row erupted and Dave demanded the truth. Kirstie says: “He asked me if I loved Aimee and I admitted I did.”
In January 2010, three months after Aimee moved in, Dave left.
Kirstie says: “The kids took it in their stride. Our friends and family have all come to accept us too.”
Aimee is now due to give birth to their son in October, after IVF treatment using donor sperm.
Aimee says: “I never thought I could be this happy again after losing Megan. I fell in love with my best friend, now I’m having a baby with her. Who could ask for more?”
Last night Dave said: ”Obviously, it was a shock but I’ve moved on and I wish them all the best.”