Hey, Pete did screw up...but you have to remember that in addition to the potential for pregnancy or disease, with a Werewolf there is the certainty of making a new (and improved?) Werewolf out of your lover.
Peter probably
had the "basics" in Human Reproduction in school...he did mention falling asleep in Biology...but there are certain basics that you just can't miss in High School.
What everybody seems to have missed, is that he didn't have to have had
"Enjoyment" with Sarah to Were' her. They probably had been
Kissing quite a bit...hello! Swapping Spit ought to do the Job (bodily fluids & enzymes).
So, Sarah was probably in a "Were" way before their "Enjoyment" and her giving up her Virginity to Peter. Peter's only other experience in this particular thing didn't result in anything but mutual pleasure with Jean (one hopes). Nothing happened because she was already a Werewolf! So, Peter really didn't have any particular reason to think there was anything to worry about, assuming he was capable of thought at that point. As I remember...thinking wasn't really "up there" in my paradigms at the time.....
So...it really wasn't the "Enjoyment" that Were'd her...it was the "Warm-up" before that did the job. I'm guessing that there was kissing before...simply because of human/were responses to that sort of situation.
KMacK...
"You don't have to be invisible when everybody is looking the wrong way..."
Writing the series "Wulfen Blood"... getting ready for publication.