Depiction of married romance

In watching this series decades after first seeing it as a boy, I've noticed how it differs from so many 1950s/early 1960s sitcoms in one interesting way. While most married couples display no more than an affectionate peck on the cheek, Jim & Margaret still kiss each other like they mean it. They come across as still being deeply in love, still romantic after 20+ years of marriage & 3 children. I don't recall seeing that much on other family sitcoms of the period.