Geri Horner says the Spice Girls all have "different priorities" now.
The girl group - which also includes Emma Bunton, Mel B, Mel C and Victoria Beckham - are trying to work out plans for a reunion but Geri admits their "commonality" has changed now.
She said: "20 years on, people move in different directions, and have different priorities ... I adore them but our commonality is different now. We all have a common ground of wanting to please our fans, focusing on the future and sharing our knowledge with the next generation."
And the 45-year-old singer enjoyed being in a "little bubble" with her bandmates during the height of their fame.
Speaking on Steve Wright In The Afternoon on BBC Radio 2, she added: "I think my favourite bits were just the small moments, when we were in our little bubble. I also liked the banter with the girls. I was holding onto Spice Girls ... but I realised for the last 10 years, after releasing an album, I changed."
Meanwhile, Geri previously likened being in the Spice Girls to a "marriage".
She shared: "[It's like] a marriage. We got together when we were in our early 20s. Emma was 18. 20 years have passed. And to have that connection and maintain it, find that commonality, sometimes you have got to ... hold on to that ...
"We're talking about [a reunion]. We want to do something for our fans and the new generation. We are putting all the possibilities out there so watch this space ... It's brilliant. We got back in the room together and said, 'Yes. Let's do something. Everyone has busy lives. We've all got children and different careers. So to get them all in a room was lovely. I did actually give them some chocolate brownies that I made. There's something wonderful about making food and bringing people together."
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