It's a combo. The girls definitely have a slight emotional instability (ie going on a reality show to hopefully get engaged to a guy you're going on 5 dates with), but I think the producers probably feed those girls booze all day so by the time evening rolls around they're wasted and thus drama ensues. Most of their eyes are glossed over during the rose ceremonies.
I can see this happening. This reasoning is solid.
My best friend and I watch it in real time together and text each other making fun of it.
I'm pretty sure my female friends do this as well. They told me they watch it too.