Father suspected of fatally stabbing family of four in NYC murder-suicide

A father fatally stabbed his fiancée and their two young children in their NYC apartment before killing himself.
The bodies were discovered after the father's relatives requested a wellness check.
There were no prior domestic incident reports or signs of distress.
The father was under stress about moving his family from the city to the suburbs.
The investigation into the motive and circumstances of the tragedy is ongoing.