If you think the Victorians typically used condoms or only had sex in wedlock then you're quite mistaken.

"Conservative" = cautiously moderate, i.e. in this instance, not engaging in sex with reckless abandon, but rather with caution and moderation.

If you think "Victorians" are what is meant when someone refers to a conservative society, then you might need to read a few more books. Its quite possible to be conservative on the subject of sexual activity, while also voting Democrat.