A little bit of back context is that the girl was a massive Sunderland fan and he was her favourite player by far, she basically just wanted a couple of shirts signing, he spotted her on social media, did the signing, and then started grooming her to meet him from then on. As I understand it that is the considered the more severe offence than perhaps going to a club or party and then having sex or drunken sex with an underage girl, because there was deliberate intent to groom a child for sexual purposes.
He has history of following other women around social media, texting, maybe even cheating. He's already admitted to contacting them. This seems like an extension of that, but the fact he knew she was 15 and pursued it is the problem.