I really don’t think Emily being with James is a mad conspiracy to get close to Danny/McFly. Danny is married with a child, Emily loves herself but she’s not that stupid. Danny has met Emily numerous times over the years and he hasn’t ditched his life to run off with her. She hasn’t wasted 3 years of her life in a relationship to get close to Danny. I would say it’s years since James has even seen Danny tbh, they’re not close anymore.
I definitely think initially for her it was a bit thrilling to be dating a “popstar” with ties to her favourite band and the houses/lifestyle James has, but at some point I do think she became very invested in the relationship which is why she can’t let it go. She’s come too far and has hyped the relationship too much, she probably wants to try save face. I’d say half of it is the clout that she thinks she has by dating him, the other half is that she actually does love him.
Also, we have no idea what is actually going on. I have a feeling that James can be very manipulative. I wouldn’t be surprised if he lied about how long he was going to be in LA for and has possibly told her he was coming home a few times only to cancel it. James may think she’s the love of his life, but it certainly doesn’t show it.