As any psychologist, advice columnist, bartender, or gal-pal at happy hour will tell you, a crucial part of any successful long-term relationship trust. Trust that your partner is the person he/she says he/she is. Trust that they're not cheating on you. Trust that when you tell them things of a confidential nature, it goes no further than the two of you. Trust that they're not going to, say, trade on material non-public information you mention to them. And to some extent, this lady had that. Her boyfriend didn't hop on his e-trade account and start making transactions every time she told him about stuff going on at work, though he did tell his father about that stuff, which was inside info, and that guy, well...y'know.
Let this be a lesson.