Okay, this is just silly. There's a post over at Newsarama snickering about the fact that a Flashpoint image of Mera features her wearing the same helmet as Flashpoint's Wonder Woman.
It's pretty simple, really. It's originally Mera's helmet, Wonder Woman kills her (taking the helmet as a trophy), and that's why Aquaman really wants to kill Wonder Woman.
It's not that hard to put two and two together, people.