It should come as no great surprise that in the event of Police being called to a domestic incident the male partner is the one most likely to be arrested.
Domestic assaults/disputes almost always have no independant witnesses, just husband and wife each making allegations against each other.
The number one priority for the Police will be to prevent a breach of the peace recurring so one of the two have to be removed. Especially where there are children in the house we as a society assume the woman is the best person to look after them, removing the man is by far the easiest way to achieve the objective.
It’s not right and it’s not fair but that’s just the way it is.