Most parents suffer through seeing their children do incredibly stupid things. Clark's parents were spared the bulk of that experience, so they never had to 'mend the fences' with him. Because of that, they can be more frank and open with him concerning personal subjects like his sex life. Or lack thereof.
This is a very interesting twist to the pheremone episode, and I wonder how much angrier this Lois is going to be when she crashes. Somehow I doubt it will be pretty, but I'd bet dollars to doughnuts that Clark's going to bear the brunt of it no matter what happens. It would be way too easy for Lois to retain her passion for him. Besides, she still has several dozen languages to go.
