Here is the full list of all 27 One Night Stand achievements. It takes around 1-2 hours to unlock all of the achievements on Windows.
You might want to double check the evidence...
You receive another message from Gary.
You both felt the same way about the book, her writing and Love IRL.
You investigated every item in the game.
You got thrown out without your clothes.
She picked up her six-string.
You got thrown out with your clothes on.
Accuse her of drugging you.
Escaped during her moment of need.
You choose to remain silent whenever possible.
You made a break for it.
You got caught wearing her underwear.
That's why they call it a one night stand.
Order a fancy coffee.
You chose not to believe anything.
You told her the last name that she wanted to hear.
What’s in a name anyway?
Honesty really is the best policy.
Turns out you share the same name!
You became a fan of Love IRL.
You became friends.
Sharing isn't caring.
Escaped quickly and clothed.
You failed at the last hurdle.
You got thrown out.
You successfully stole a pair of her panties.
You got rejected.