This is a hard truth, but it is the truth.
Those who are Catholic must believe in life-long monogamy sanctified in marriage.
Those who abandon the belief in the practice of life-long monogamy have lost the Faith.
Now, I don't think that's controversial.
What is controversial, is the degree to which this value must be supported by social pressure and accommodations.
Liberals of course, basically act as though it can exist in a vacuum, that it's the ideal, but people are weak, we can't really expect it, it's just a nice idea, something shoot for, not something that we can organize our lives or society or laws around.
A true traditionalist, on the other hand, is aghast at the breakdown of marriage and recognizes the factors leading to the breakdown of marriage.
A true traditionalist values the ideals and morals of the past.
Whether it's the matter of the size of families
The age at marriage
The importance of innocent courtship
The importance of priority for marriage and motherhood for young women
The importance of taking steps to protect the innocence of young women
The importance of maintaining the honor of purity
The importance of avoiding divorce.
All these things are critically important to serious traditionalist, but to a liberal, they are all rather inconvenient ideals that have to be made optional, inessential, adjustable, or just discarded for the sake of practicality. Sure, they will say, in a "perfect world" things could be that way, but we're all frail human beings we can't actually expect almost anyone to behave that way!
Now the reality of human nature is such that feminism is diametrically opposed to the traditional conception of marriage. In fact that is it's reason for being. That is it's real purpose. Everything in feminism is about circuмventing the controls that were imposed on women to ensure the welfare of posterity.
Of course, those who support careerism in women can deny that all day.
They are disingenuous or deluded.