For me that interpretation isnt logical. There is no rationale or biblical support for why a legally & religiously married couple would abstain from sex. The catholic belief of perpetual virginity is pure opinion.
Well, how about a cultural belief? Being a Filipino I am sure you can see this one. As a Hispanic my first cousins are called my brothers and sisters their children are my nephews and nieces. As for your second comment here what makes your opinion (how old are early 20’s?

) more viable than the Church’s 2000 years?
i think morality is an integral part to human society. but you cannot call “moral” something that causes more harm than good. and prohibiting artificial contraception in this day & age is more harm than good.