Cowell announced in February last year (10) that he had become engaged to make-up artist Mezhgan Hussainy, sparking frenzied speculation about when the nuptials will take place.
The X Factor boss has still not revealed any details of his wedding, and his former girlfriend Sinitta has now cast doubt over it - suggesting he no longer spends "so much time" with his fiancee.
She tells Britain's Weekend magazine, "When he and Mezhgan first got engaged, he was besotted. I thought, 'OK, he's gone. I've lost him. He's head over heels.'
"It wasn't like a knife in my heart but it was strange to watch him. I'd never seen him like that with anyone before, and I was going through a divorce, so I probably was lonely. It seemed to come from nowhere so I was quite stunned... Now they don't spend so much time together. I've only seen her with him once this year... I really don't know if they'll get married."