Former TOWIE star Lewis fell for Marnie in the summer series of CBB, hooking up with her in the house and exchanging 'I love yous'.
Now out of the house, they're giving their relationship a real go.
It raised some eyebrows as Geordie Shore's Marnie was previously engaged to TOWIE star Ricky, who shared the screen with Lewis.
But speaking to New magazine, Lewis, 26, downplayed the idea he was friends with Ricky, 25, saying: "Ricky and me only ever saw each other when we filmed TOWIE. "
Lewis said after paparazzi pictures were published last year showing him and Marnie, 24, in a cab together, Ricky called him to ask what had happened, but Lewis assured him nothing had.
"We haven't seen each other since," he added. "If he wants to call me and talk about it, he has my number. But that's not his woman. I love that girl and she's my girlfriend."
When Lewis and Marnie first got together on CBB, reality star Ricky spoke out saying he heard they'd kissed on a night out in the past.
But a rep for Lewis and Marnie firmly denied they'd had a romance before the show. As the pair share an agent, there had been rumblings of a pre-planned showmance, but the spokesperson said that wasn't true.
Lewis previously discussed those pap pictures during an appearance on Loose Women, saying while it may look as if they knew each other before CBB, their paths had only crossed once.
"Me and Marnie have met once briefly before about a year ago and at the time there were some pap pictures put up which were unfortunate for her ex Ricky. He rang me about it and said, 'What's happened? Did you go home together?' We got in a cab with a bunch of people, there were three taxis, from one club to another. We hadn't seen each other since," said Lewis.
"When I say the best thing about my experience is meeting Marnie it's because we saw each other at an event, it was business, it was for work. We met each other how we are in [the CBB house]."