In unaired scenes, ex-TOWIE star Lewis bravely asked Bear for his honest opinion on whether he saw Lewis and Marnie as a couple six months down the line.
"Honestly?" said Bear. "No."
Marnie, who was sitting with them, described Bear's answer as "like a bullet" as it was so quick, while Lewis pointed out Bear's "been through some s**t" in past relationships.
But Bear didn't back down. "From past experience [that's what I think]. I could be wrong and I want you to prove me wrong. Now you have the hump. Brilliant. You wanted an honest opinion and I say no. If you are, I'll say f**king well done."
Lewis argued: "I have dated enough girls, she's dated enough boys. Maybe it's just we're in here…"
"It's different circumstances, man," said Bear.
Lewis also admitted he's never had a "celebrity girlfriend" before, prompting Bear, who has dated Vicky Pattison and Lillie Lexie Gregg, to say: "Mate, it's the worst girlfriend to have. Your nut goes wow. Celebrity girlfriends. Tried and tested. Nightmare. The worst."
But Lewis argued: "[Marnie] is a sweetheart who happens to be famous."
Bear replied: "That's what I thought, mate. Listen. It's not my business."
Lewis and Geordie Shore's Marnie have already exchanged 'I love yous' despite only being in the house for three weeks. They've been accused of setting up a showmance after it emerged they share an agent, but their rep has denied this, insisting they'd only met once in passing before the show.
CBB continues 9pm on Channel 5.