While the redhead insisted there was no feud between Ulster girl Nadine and the rest of the group, she told Hello! that they have not heard from her since the autumn.
The band have taken a year off to pursue solo projects, with Nadine now based in Los Angeles.
Roberts said: “If I'm really honest, we haven't spoken to Nadine since we did the Coldplay gig at Wembley in September.
“I talked to the other girls about it on Monday and no, none of us have heard from her. But there's no feud.”
The time off has given the 24-year-old the chance to have “girlie chats” while visiting the other band members' houses — Nicola now lives in Weybridge, Surrey with boyfriend Charlie Fennell. She said: “You can just go round, curl up in your tracksuit on the couch and chill and talk about anything and everything.”
She added that the girls’ partners have to earn the approval of the other band members.
“We're like that film Meet the Fockers — we have a circle of trust and you have to earn your place in it. I wouldn't ever want to bring someone in just because I was smitten; lust can glaze your eyes over and you can make poor judgments.”
The full interview appears in Hello! magazine which is out now
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Your dry humour will be very popular. It's always difficult bringing a large group of people together. Everybody feels like they are walking on eggshells. After cracking a few jokes, you'll put the group at ease. Resist the temptation to make fun of relatives, especially the more sensitive members of the group. Nobody likes feeling singled out. Watching a light hearted comedy can also be a great way to generate a festive atmosphere. This is a time when people can put their differences aside.More