Ummm...........guess we don't want to be perceived as cheap and easy even though we do have sexual desires of our own?
I know in my case my mom told me literally every day of my teen life that if I slept with a guy before marriage I would be 'trash' and a 'slut'....there goes that family of origin creeping in! I lied and let her think Dan and I waited--granted we did wait 2 years.
In my case I think there is just an inner conflict between "Hey it's been two years, come ON"...and "Sex right out of the gate is not what I am used to"...