The Welshman was originally hosting the new US talent show along with Nicole Scherzinger but she then became a judge and replaced Cheryl, 28, when she was kicked off the show.
Speaking about Cheryl's exit, he said to UK's Heat magazine: 'It was business as usual. You can't really mope around.
'I was really looking forward to spending a lot of time with Cheryl - I've known her for years and she's a great girl.
'But we just got on with the show. We moved the pieces around and just continued. What else can you do.'