She said: "He's always quite romantic. But the most romantic thing is he wants to make me happy. I've always wanted to get married one day and have my own family."
The former S Club Juniors singer - who started dating Dougie over a year ago - admits she knew she was "right" for the musician before they even met.
She added: "I knew we'd get on, even before we'd actually met. When we were younger, magazines would often ask him who he liked and he'd always say me, even though he didn't really know me.
"When I was in S Club Juniors I thought he seemed nice, and when we met I was like, 'yeah, this is definitely right."
However, the 21-year-old beauty admits she would make her boyfriend "suffer" if she ever found out he had cheated on her.
She added: "If I killed him he wouldn't be able to suffer! I would probably torture him though, and go mental.
"It would be such a shock if he did cheat though, I'm not going to lie."