"The hurt person is buried in an avalanche of losses," she told ABCNews.com. "It doesn't just involve a loss of trust, but the basic loss of self. It cuts to the core."
Spring said hurt partners experience feelings of being "helpless, crazy and alone."
"They become obsessed with the affair and the other person," she said. "They spend all their time checking, looking at the partner's cell phone and emails because they don't feel safe."
Spring said physical symptoms, such as those experienced by Trierweiler, are not uncommon.
"People experience disorientation, not sleeping," she said. "Because they don't sleep, they don't function well during the day. They go to the parking lot and can't find their car. They get lost in their mind. It feels like it's been hijacked."
She said it doesn't matter if the hurt partner is married or not. The trauma is still there.
"Betrayal is not about marriage. It's about one person believing they are in a committed relationship and the other acts outside of the contract," said Spring. "Affairs are not about sex but about secrets."