You shouldn't do sketchy things around your partner.
James frequently smokes meth, but his girlfriend has never tried drugs.
James wants to feel accepted by his girlfriend.
James tells his girlfriend about his meth use but only smokes when he's alone.
James smokes meth in front of his girlfriend on a regular basis.
James' girlfriend accepts his drug use as long as he maintains steady employment.
James' girlfriend eventually asks to try the drug and becomes a regular user.