Kasen is an interesting case, mainly because there's a whole lot we don't know.

On one hand, she's most-likely not a virgin, though the situation or occurrence of how she lost her virginity is probably a bit of a puzzle.

Katherine on the other hand is a little more straightforwards.

She was actually sober during her first time, which happened with one of the first (relatively) serious attempted relationships she had during her teenage years.