Killer Instincts

Harry is a happily married Auror, who realises that the past can't always resolve itself when he meets Ginny on a case. Ron and Hermione, on the other hand, seem to be tired of each other. Tempers are running high and the patience is waning. Is their marriage going downhill? And will the Aurors find the person responsible for the London serial killings? HP/GW (slow build) & RW/HrG