The 32-year-old, who played Dr Matt Carter in the soap, has revealed how the pair fell in love during filming.
Despite both parties being in other relationships at the time, 37-year-old Kym in a marriage to Jamie Lomas- the father of her youngest child, and Oliver in a five-year relationship with a PR, the father-of-two admits they couldn’t stop themselves.
“We were in love and planned a future together,” he remembers.
“We loved each other and we weren’t afraid to say it. It wasn’t something we intended to happen, but we couldn’t stop our feelings.
“We planned a future together. We dreamed about me moving up North and living together. We spoke of how wonderful life would be.”
“The last thing Kym wanted to do was hurt anyone,” says Oliver. “And she knew what we were doing could have serious consequences for everyone.
"But the fact we were both willing to take those risks when the stakes were so high shows how much it meant.
“It wasn’t something either of us took lightly. It was the beginning of something long-term, not just a flippant, physical thing.
"We really cared for each other – and I thought we’d stick together.”
Oliver joined the Street as Dr Matt Carter in 2010. But he says the affair only started in February 2013 – five months after she sold pictures of her wedding to actor Jamie Lomas to a magazine in a six-figure deal.
“I knew she was married to Jamie Lomas. I’d seen the wedding photos in a magazine. I asked her about it and she told me I’d been invited. But I think it had been sent via Corrie and got lost.
"We laughed about how it would be weird if I had gone and there had been pictures of us all together on her big day.”
Kym told Oliver several times her relationship with Jamie, 33, was coming to an end, but he began fearing it never would and at the end of July their affair ended.
Oliver is now in a happy relationship, and Kym and Jamie have since divorced.