I have a gf and she wants 2 b exclusive, but when we get to school i have to pretend that it aint true. y?

we have been dating for a week going on two. we really are into each other a lot. we talk everyday and hangout after school everyday. and she said she really really likes me and she is happy that im her gf too but i dont like keeping it on the DL when i'm at school. i like showing pda and she says it doesnt matter except for at school.