The Newcastle-based Geordie Shore favourite fell for former TOWIE star Lewis, who lives in Essex, when they appeared together in Celebrity Big Brother earlier this year.
They had seemed blissfully smitten with each other inside the house, and after they left the show, the couple turned down photoshoots and interviews together, saying they wanted to keep their romance away from the spotlight in order to make it work.
But rumours of a split surfaced last week when Marnie deleted all trace of Lewis from her social media accounts.
On Wednesday's episode of Loose Women, Marnie cleared up the situation, saying she'd deleted the images after an argument with Lewis but they were working past that now.
"It's really tough because we live so far away from each other," she explained.
"We had an argument and I deleted every picture of him on Instagram. I was really angry and immature and forgot everyone can look at it. I thought, 'Why have I done that?! I've put so much pressure on us.'
"It's hard, but we're working through it."
"Things on the outside are very different to how they are [inside the CBB house] and we have kind of got a completely different relationship to what we had in there, so it's back to basics."
Marnie confirmed that she "100 per cent" loves Lewis, adding: "I haven't seen him in two days and I'm a mess, crying every night."
She also said her decision to return to Geordie Shore hadn't affected their romance, saying: "I've been in there with a relationship in the past and it's tough but i got through it. And I hadn't cared about anyone like I do about Lewis."
Marnie has previously spoken about the difficulties of a long distance relationship, writing in her Star magazine column: "Things are still going well between me and Lewis but I find our relationship really hard, if I'm honest. I want things to be as amazing as they were on CBB but I was being unrealistic because it's so different outside.
"I want to keep things private because I don't want to give people a reason to talk about us. I already get tweets when he's doing PAs. It's so stressful."