Erik C. Grumpelt, 35, was arrested on Monday, the Mesa Police Department said in a news release.
39-year-old Malinda Raya was found in an advanced state of decomposition on the bedroom floor of the apartment, covered in several sheets.
Police say Grumpelt told them he had repeatedly struck Raya in the lower abdomen after she said she had cheated on him.
There were several room fresheners found in the bedroom, and powder, believed to be carpet freshener, was sprinkled on the area around where the victim lay.
Grumpelt told investigators he assaulted Raya on the morning of May 19, striking her several times in the lower abdominal area while laying on their bed.
He left for a short period of time and when he returned, she was unresponsive.
Grumpelt said he was angry because Raya had told him she had cheated on him with other men in his bed.
Raya was a mother of two, according to reports.