The Girls Aloud singer says the Dancing With The Stars hunk, 25, makes her happy.
'Derek is a sweetheart,' says Cheryl, 27.
'The kind of person who makes the day more enjoyable... and that's important.'
Cheryl was introduced to Derek when Strictly Come Dancing judge Bruno Tonioli recommended him to star in the video for her single Parachute earlier this year.
'Bruno said he had the perfect person and that's how I met Derek,' The X Factor judge says in new book Through My Eyes.
'Parachute is the story of a relationship with someone who's there no matter what.'
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