Responses
It seemed that the father cheated or in the mother's words "loved many people".
The day she died the father told taiga to go to the hospital first and he would come later. When taiga saw his father he was holding a basket of flowers and taiga thought his dad bought those flowers for another woman.
Actually that day he bought them for the mom but he couldn't make it because he went to save arima who he thought was a girl and gave him a flower.
Ohhh thanks ლ(´ڡ`ლ)
But what did his father do to his wife i didnt understand