Death of wife some combinations as per astrology.

 The dead woman's body. Focus on hand - stock photo
Death suicide or murder of wife ( some combinations from sarvarath chintamani).
Lf the lord of the 5th house is located in the 7th, and the lord of the 7th house is with a malefic and Venus is weak. the wife of the native dies as a result of (loss etc of) pregnancy. (1 I)
If the 7th house is occupied by Venus in its sign of debily it or if Moon is in its sign of debilitation in the 7th house the wife dies by drowning. If the lord of the 7th house is located in the decante going by the name Paasha &  Bhujung (Rope & serpent) the wife dies by hanging. ( 12)
If the lord of the the 7th house is with Rahu and Mandi and is in decantegoing by the  of Bhujanga i.e. serpent the wife dies by taking poison.