I think "Reality Ensues" would actually be a better trope.
Okay, let's just take a look at all the non-supernatural things that happen over the eight month span that is season 6. I'm going to be focusing on Buffy's point of view because she is the main character. I'll try to be as unbiased and factual as possible in the descriptions.
- Buffy begins the season suffering from major depression due to believable issues.
- Buffy's father figure leaves her during her depression to force her to stand on her own two feet.
- Buffy's best friend, Willow, becomes addicted to drugs and her girlfriend breaks up with her over it
- Buffy's kid sister turns to stealing for attention.
- Buffy's other best friend, Xander, has a great job and is engaged to marry his long-time girlfriend. Buffy sees their happy relationship as the light at the end of the tunnel for her. Xander leaves Anya at the altar over fears of becoming his father.
- Buffy, despite working for an organization that pays her advisor/mentor a living wage, receives nothing herself and is forced to take a fast food job to pay the rent. The two other adults (Willow and Tara) living in her house contribute little to nothing.
- Buffy enters into an abusive relationship with a man she hates just so she can feel something in her life.
- Buffy's old boyfriend, who she had loved and lost, shows up out of the blue happily married to another woman.
- While a madman is attempting to shoot Buffy, one of his stray bullets travels towards her house, takes a 90° left turn towards the window, and kills Willow's girlfriend. Willow then has a breakdown and goes super hardcore into drugs.
Sure, all of these things taken individually is realistic (except the last), but all of this shit happening around the same time to the same group of people? It's completely ridiculous. If this is reality to you than I suggest you call Wolfram & Hart and ask for Ritual Sacrifice because you have seriously pissed off a god or two.
A good example of Reality Ensues would be Joyce's death. It was a very traumatic event that all of us could relate to, or, at the very least, image this happening to us at some point in the future. It felt real. Of course, it's important to remember that at this point most of the characters were relatively happy. They had their problems (Glory for one), but it wasn't all doom and gloom. The myth is that life is pain, but the reality is that life is both pain and pleasure. As soon as you forget one in favour of the other your work becomes unrealistic. That's what happened in Buffy season six.