I do not think we can generalise here. Perhaps one never can when discussing human behaviour.
My experience as a school-teacher has shown me very clearly that many parents are unable to see faults in their children, or indeed any difficulties the child might have ,be they learning difficulties, or behavioural issues.
I suspect to a certain extent we all see our children as extensions of ourselves, that our love for them, and theirs for us, blinds us to a certain extent to the less acceptable sides of them, and that guilt if a child, whether as a child or and adult, does something wrong also plays a part.
And of course this applies to the love between spouses as well.
I think there have to be limits, not to our love for parents, children, husband or wife, sisters, brothers, friends, but to our tolerance of their behaviour and that the limit must be reached, when we see them either harming themselves, or harming others (including us).
Enabling a drug addict, or an alcoholic (to take two common examples) is surely wrong, as whatever the addict may say, it is not in their best interest that we help them to continue along their self-destructive path.
Nor can it ever be morally right to conceal that anyone, family member or not, is potentially or actually harming others, is contemplating a crime, or has committed one.
In most countries, it is a crime not to report a crime that you know has been committed,or one that is being contemplated.
Concealing crimes will probably lead to you being charged as complicit, or an accessory.
In our lifetime, attitudes have changed regarding many things that we were brought up to believe were wrong. Many of these changes are all to the good, but,l ike anything else, tolerance can be carried too far.
So to my mind, there needs to be limits to our tolerance, and we need to make moral and ethical decisions when confronted with cruelty in any form, or criminal behaviour.
But there should not be limits not to our love, but to any acceptance of wrong-doing. It would be the epitome of selfishness only to love those who treats as well! But by actively concealing wrong-doing, we are subject society as such, potentially, or in actual fact to it.