James Morley admitted the culpable homicide of 46-year-old Elaine Duncan at a property in Newmilns, Ayrshire, on April 18 this year.
But prosecutors rejected his plea at the High Court in Glasgow and Morley will now stand trial accused of murder. He also faces separate charges of assaulting a man and behaving in a threatening and abusive manner at a pub in Newmilns, which the 40 year-old denies.
Judge Lord Uist set a trial due to begin in December.
It is expected to last around 10 days.