There is, I think, a single grain of truth that spouses should put each other first: They need to work together to raise well-rounded children who will then hopefully leave home to found their own families - a situation that, like retirement, leaves spouses closer together and with less destraction than when they were younger. Kids are supposed to grow and go, and they do better if their parents - assuming the parents aren't fucking insane - are unified and committed to each other; to making space for private time together. It's not good when the founding relationship disappears as both parents become so engrossed in child-rearing that they lose sight of each other.
BUT this quote goes far beyond that, especially when the OP claims the sexual relationship confers more 'oneness' than does having another being growing inside you for more than nine months. That's rediculous: Having children who grew nourished entirely by your own flesh is a different kind of oneness than the decision to love someone and - among some people - build a relationship that can outlast the empty nest.
What bothers me so much about this - and that whole idiotic site is a rich mine of backward and distorted "thinking" - is just how little basic human respect fundie parents have for all their "blessings."
On the one hand, motherhood is allegedly a zero-sum calling whereas on the other children are treated as chattel, often poorly educated in these circles, dismissed, used - overtly; some fundies, such as Nancy Campbell, brag about this - to take over most if not all the household chores as they grow. They're not allowed to develop normally but are terrorised into obedience at young ages by methods such as "blanket training" (which is useful for lazy parents, for ignorant parents, or for parents with 15 other kids), stunted, sometimes denied proper and even life-saving medical care. The list goes on.
There's a huge difference between spoiling a child and meeting their basic needs; between overindulging a child and ensuring the kids aren't sleeping four to a bed because their moron parents decided to have eight kids when they can only afford a two-bedroom apartment.
All of that and more is the subtext for the article I quoted. (And has anyone, anywhere, gone to a family gathering where children not only eat with adults - heaven forefend! - but sit at the head of the fucking table? Yeah - me neither. Yeah, me neither.)