Justice League: The Flashpoint Paradox is the newest animated superhero film, an adaptation of the 2011 comic book crossover "Flashpoint" by Geoff Johns and Andy Kubert. Directed by Jay Oliva and scripted by Jim Krieg, this is the 17th film in the DC Universe Animated Original Movies series.
After an alliance between the Atlanteans and the Amazons, Aquaman and Princess Diana slept together, but are seen by Queen Mera (Aquaman's wife). Mera confronts Diana leading to a fight which results in Mera's death. Diana wears Mera's crown as a trophy, and Aquaman declares war on the Amazons.
Does it look familiar?