My gf is leavin 4 two weeks an is really insecure...what can i do before she leaves ?

she is very insecure and is so scared i will leave or hang with chicks or change my feelings b4 she gets back...what can i do to show her that i care an something like a cute idea idk something i could give her b4 she leaves or say .....i plan on writing a note for every day she is gone but idk wat else to do