You are judging that from your perspective in a Western society, which , despite its many flaws, will generally support , at least morally, a single mother looking after her children, much more than a woman leaving them behind.
There are several countries where women do not have any rights over their children, the wife is a chattel , and if she leaves, it will be alone. It is therefore very painful, but not abnormal, sadly, for them to leave, or indeed be kicked out, alone and without another man.
I am not alluding to specific faiths here, as I do not know whether that is the case, but it is certainly the case in the Middle Eastern countries where my friend is from, that the rule of faith is the law of the land , and she has no rights in this.