You're probably missing the context of it. See, a whole bunch of people seem to think that the more sex a woman has, the bigger her labia get. It makes no sense, obviously, but that's what these fucking morons believe. Add to that the other bit of context, which is that those same people generally are men who hate women, and believe that women should be essentially property.
So what this dicknose is saying is that his daughter is a good, wholesome Christian who would never have sex out of wedlock, and thus avoid having her private bits stretched, unlike godless heathens like Taylor Swift (who is also Christian, btw), who have sex all the time with multiple partners because of their twisted, perverted natures.
I'm still waiting for a convincing explanation as to why if repeated sex will stretch out your labia, it only happens when you have sex with different partners rather than with the same partner. Some kind of weird mental gymnastics at play for that one.
Because obviously being a giant slut means only sleeping with guys with huge dicks. This guy obviously doesn't have one, so that must be why his wife has a small labia. So throw in penis envy onto this guy's pile of issues.