"I do everything to make u happy and to not say anything to rock the boat with u. You do everything to throw tantrums in front of people," she wrote. "I just want to love and be loved. Be happy and make someone SO happy. Maybe we can't do that for each other. Cos right now I know u aren't happy and I am certainly very unhappy and sad."
A handful of texts recovered from Steenkamp's iPhone were read aloud in a South African courtroom earlier this week where Oscar Pistorius, 27, is standing trial for the premeditated murder of his girlfriend, who was a law grad and model.
The star athlete admits to killing Steenkamp on Valentine's Day 2013, but says he thought she was an intruder. But prosecutors are attempting to paint a picture of a trigger-happy man with a quick temper.
Despite the couple's volatile relationship, Steenkamp's texts also reveal how she felt about him. "I am the girl who let go with u even when I was scared out of my mind to, I'm the girl who fell in love with u and wanted to tell u this weekend."
For an inside look at the Pistorius trial, pick up the latest issue of PEOPLE, on newsstands Friday.