The duo, Hollyoaks' Will Savage and Theresa McQueen, told Cosmopolitan that they had tried to keep their romance quiet while their characters were also being paired up.
"When James walked into his Hollyoaks audition 12 months ago, he grabbed my attention straight away," Porter recalled. "He got the part and we immediately gelled. Then he returned from a holiday and rolled up his sleeves to reveal big tanned, sexy biceps. I was like, 'Wow!' After that I couldn't stop thinking about him.
"When we did a stint of late-night filming, we really started falling for each other. We kept it a secret at first, which was stressful but exciting. Every time he brushed past me, I felt all giddy."
She continued: "When our characters had to do their first on-screen kiss, we had to pretend it was our first time when really we'd been secretly snogging for weeks!"
However, the Dancing on Ice favourite admitted that attempting to be moody with Atherton at work was "a total waste of energy", joking: "He wouldn't even notice! But it's lovely to share your work day with someone."
Describing their first date, he said: "[It] was crazy golf and we said whoever got the first hole-in-one had to give the other a kiss. So our first kiss was on the volcano challenge of a crazy golf course - not on the set of Hollyoaks."
The full interview appears in the March issue of Cosmopolitan, out now.
> Jorgie Porter: 'Dancing on Ice makes me too tired for sex'
> Hollyoaks Jorgie Porter: 'Upset ahead for Theresa'