Many (most) parents would not permit their 15 year old daughter, to go to a drinking party with 17 year old boys.
In part it is because they don't want her involved with precisely what they remember from when they were 15 and 17 years old.
The brains and personalities of such young people are not fully formed.
A 15 year old girls might not yet know better, than to go around teasing the boys. And a 17 year old boy,, teased in certain ways by a 15 year old girld might take it as an invitation.
Being young, sexually naive and/or clumsy they might wind up on the bed, etc. Pushing, pulling, fallling. Being pushed.