But Brianne York said Sunday that Belcher and his girlfriend, Kasandra M. Perkins, had gotten back together by Thanksgiving.
She said they had argued about "normal couple issues" and Perkins had gone to visit her family in Texas and briefly stayed with her cousin, who is married to Chiefs player Jamaal Charles.
Recently, she said, the couple "seemed fine."
She thought there was a mistake when she learned that Belcher killed Perkins at the couple's home Saturday.
Police said Belcher then drove to Arrowhead Stadium, where he thanked his coach and fatally shot himself.
Belcher and Perkins had a 3-month-old daughter.
Police didn't release any additional information Sunday.