I think she can have kids (that’s why his family kept pestering them) but he’s too much of a narcissistic bully so that’s what’s stopping her from having one, if she got pregnant there would be bunting all over Essex, then once the excitement died down he would be calling her fat whilst she’s pregnant and once she had the baby too. That’s one thing she has control over (her eggs).
It’s killing him that some of his friends and not to mention his brother and sister have beaten him to it, it makes him feel a failure.