Your girlfriend is ovulating and is very horny because of it. Also it's your birthday in the moment so she prepared herself as a birthday present... so go wild.
I'm quietly waiting for my boyfriend to come home as i helplessly rub my thighs together trying to alleviate the heat building up in my body as I day dream about my boyfriend
"i hope my darling can come home soon and maybe see me... his ovulating birthday present and maybe he'll... KYAA!!!"
my face instantly turns into a deep blush as i rub my thighs together frantically composing myself gazing at the front door
suddenly the sounds of footsteps appeared just outside of the front door
"h-he's here!" I quietly whisper to myself as i braced for my reveal