hi Iris8 and

im glad you worked up the courage to post. i know posting on a message board forum for the first time can seem kinda foreign.
it sounds like you care a great deal for your friend. living with BPD obviously isnt easy, and people with BPD tend to function better with strong and empathetic people in their lives, who care and support, but with strong boundaries.
i can understand where she comes from in terms of taking job rejections personally, its difficult not to, and the experience can at the very least, be very discouraging. that is something you can probably validate, without validating the invalid (the things she believes about herself as a result).
as far as leaving her alone, i can understand why you would feel guilty. i think its important to remember the old adage about in flight oxygen masks. if you arent living your life, and seeking your own happiness, its going to be difficult to be supportive to someone else. her fears and feelings about herself are deep seated, and not something you can cure. have you invited her on these outings, or out in general? she might decline, but still appreciate the offer. i know as an introvert i decline a lot of offers, but still really appreciate them, and dont like feeling left out.