Lena was absolutely right though about Kara's unprofessional behavior. In the real world, Kara's absenteeism and poor attitude would have gotten her fired a long time ago.
The difference here is that her boss--James--understands her distracted behavior and has voiced true concern, not trying to artificially bond to Kara like Lena. She's just a bank account with ulterior motives, and barked at Kara for being shut out of her personal life. If Kara spilled out her issues with tear-rimmed eyes, Lena would not cop that snake attitude and instantly become just as "unprofessional" in trying to bond with Kara.
				

  Granted, she might have been mentally ill, but then again, maybe not.  I have no doubt that at some point in her life, she faced blatant racism and discrimination.  Sometimes people can't help being resentful and bitter after going through persecution.