Simon Cowell is "glowing with happiness".
The music mogul's mother Julie Cowell, 84, is astonished at the impact his lover Mezhgan Hussainy has had on him after just months of dating.
She said: "I couldn't believe it when I saw him. He looks exceptionally happy and there's such a glow about him. I think turning 50 made him reassess his life. I think he would make a wonderful husband.
"I knew it was serious when Simon said he had something important to tell me. I asked if it was good or bad and he replied, 'That depends which way you look at it.' 'Just tell me,' I said. He explained that he had asked Mezhgan to move in with him. Although girlfriends have stayed with him in the past, he has never done that before. That seemed to make it official."
Although Mezhgan - a make-up artist who first met the music mogul seven years ago - was spotted wearing a diamond ring on her wedding finger recently, Julie claims they're not yet engaged.
She told Britain's Hello! magazine: "I haven't seen the ring yet, but I do believe they will get engaged. But if you'd asked me this three weeks ago, I would have said, 'Absolutely not!'
"Now I really think marriage and fatherhood are going to happen for Simon. I would like to see an official engagement, a marriage, and yes, then grandchildren."
Simon's representative Max Clifford also insists the 'American Idol' judge is yet to pop the question, but he thinks it will happen soon.
Max - who is getting married himself in a few weeks - revealed: "I said to him, 'So, there's going to be two weddings this year?' Normally he would say, 'Don't be so ridiculous', or, 'In your wildest dreams.' But he said, 'Who knows?' "
Max also let slip that Simon and Mezhgan have been romantically involved for some time but kept their relationship secret.
He added to People: "They've actually been going out together for the last year. She knows him, she's been around him. So, she knows the person he is, and he knows the person she is. They are very well suited. She is someone who is independent and says what she thinks and feels, and he likes that. He's probably the happiest I have ever known him in the nine years I've been working with him."