Mr commitment. My legendary girlfriend

Duffy is engaged. He accepted Mel's proposal. But the trips to Ikea, dinner parties for couples and talk of babies are giving him itchy feet and now he's not sure if he can say goodbye to his extended adolescence and can face up to that final walk down the aisle. How does he know if she's The One? Can he cope with responsibility? Does he have what it takes to become Mr Commitment? Because if he doesn't, he may just find that he's lost Mel - forever...