I supported a friend through a rape trial in the 80s. The rape was awful, but the trial seemed to leave her with more long term damage. Back then, you could opt for an "old-style" committal, where witnesses gave evidence at the magistrates court before having to go through it all again at the trial itself. And the rapist sacked his legal team and represented himself at the committal, so he was the one interrogating her.
After he was convicted, she found out that he'd been acquitted of attempted rape a few weeks before he raped her.
He got seven years. She never recovered, became an alcoholic and died when she was only 53.
Thankfully, things have improved since then, but having seen what she went through I can understand why some people don't want to put themselves through giving evidence.