That is, if you tell your wife that her awful new dress looks lovely, that is a venial sin, while lying under oath is a mortal sin.
Fortunately, neither my wife nor daughter ever asked me to swear to God that it looked good. My daughter came close a few times when asking, “Do these pants make my butt look big?”
Being a basically honest type person, I would honestly answer “The
pants don’t make your butt look big”.