Quantico: Why would Alex plead guilty?

Now that everyone (probably) has watched the latest episode of the rising TV show, Quantico, let's reflect on it. While certainly entertaining, it is packed with weak immature dialog and lazy writing.

With that out of the way, lets elaborate :)

Quantico season 1 episode 9

Quantico's take on the FBI training surely reminds you of your time at high school. The characters display an absurdly "teenish" behavior, at the same time as each of them carries a supposedly very intense backstory that you would think would have helped them mature... But no, that is not the case, they all just fall madly in love with each other on first sight, and unprofessionally base their decisions on their relationship status (one would think hope the FBI recruits better candidates to be their agents). [...]