Lover Come Back - S1.E20

Tess is obsessed with her new psychology theory - the three levels of why. Armed with one of her mother's old psychology textbooks she figures if she can real reason for people's actions, then everything will be sorted. But all the psychology in the world can't explain why Alex isn't as romantic as she would like him to be, why Becky and Jodi are at each other's throats, or why Loverboy - the bull Claire sells to Nick - keeps breaking out of Nick's yards and returning to Drovers Run.