Speaking in a new interview with US Seventeen magazine, the starlet hinted at a rift between the super-famous Twi-stars, revealing the cast was 'like one big happy family' until the vampire franchise became a worldwide hit.
'In the beginning, it was innocent and fun, and we were like one big happy family - it was like being at sleepaway camp,' she said.
'And then success comes along and changes the dynamic.'
The actress also admitted the famous cast aren't all 'best friends' and probably won't stay in touch after they've finish promoting the final Twilight film.
'We’re not all best friends, and we’re not all going to hang out together after the final movie is done,' she added.
Newly-married Nikki - who tied the knot to fiance Paul McDonald just last month - has been hard at work on the Twilight publicity trail in recent weeks, jetting to Rome with Jackson Rathbone, and dazzling at the LA Gala premiere in glittering green Marchesa.
Meanwhile, Robert Pattinson and Taylor Lautner are set to appear at the UK premiere taking place Westfield Stratford tonight - and Marie Claire has bagged a front row seat! Stay tuned for all the details.