The 39-year-old actor is eager to settle down and start a family with the 22-year-old British model, whom he started dating after they met at the ELLE Style Awards in London last February, but she has confided in her best friends Cara Delevingne and Georgia May Jagger that she is worried she is too young.
A source told Yahoo Celebrity: "Suki's been texting Cara saying that Bradley wants a wedding before he's 40, but she's worried she's still too young, even though she's besotted with him.
"Cara and Georgia May [Jagger] have told her to go with it and let it happen."
The insider added: "Bradley wants children before he's an 'old' father. He adores Suki and she is happy to have children very soon - they basically want the same thing. Her best mates have told her to relax and let it happen - as long as they're bridesmaids!"
The 'American Hustle' star admitted last year that his father's death from cancer in 2011 made him think about starting a family.
He said: "Of course I have (thought about being a dad). I really hope I have that experience in my life. I saw how much joy fatherhood gave my own dad. So I hope it's part of my journey. You go through stages in your life, and fatherhood seems like a natural stage."