They are all just following the script.
Exactly. A friend of mine's girlfriend was on a reality show--a fairly obscure cable one. They'd established her boyfriend early on, but over the weeks of filming they broke up and she started dating my friend (they'd dated years before). For the sake of the show and the established story line, the producers had her and her old boyfriend pretend to still be together. In fact, they had to pretend to still be living together, with scenes filmed in their apartment, even though she'd moved out.