I really think that Anna wanted the benefits of a wedding, Sticking it to Birkhead and the money they got from the pictures, but didn't want to be legally saddled with Killa Kevin.
I don't agree that she wanted to stick it to Birkhead at all. I think she wanted to get married, but to Birkhead.
Knowing that was Anna's "wish", Stern killed her. That's my opinion at this stage. And who is Killa Kevin?