Ms Herda was taken to hospital and interviewed later by gardai about the incident.
Sources said that Ms Herda knew Mr Orsos but had become distressed in recent weeks after receiving repeated calls from him.
"This story is tragic in so many ways – officers now are establishing the exact events that led to this car being driven into the sea," said a senior source.
Sources say that Marta – who is Polish and in her mid-20s – had recently been inundated with calls from Mr Orsos.
It's believed that Mr Orsos was persistently contacting Ms Herda who felt under "extreme pressure" as a result of the attention.
However, his advances were not reciprocated and this angered Mr Orsos, who posted a series of online messages.
"He was besotted with this woman, she meant everything to him and when she told him she wasn't interested that's when his behaviour changed dramatically," said a source.
Messages posted by Mr Orsos in recent months tell friends to "leave me alone", adding that he is suffering from a "broken heart".
It was Ms Herda who raised the alarm with a security guard in the area early yesterday morning. Gardai were immediately alerted and began a search for the missing man. When gardai arrived at the scene, Ms Herda was "soaking wet".
Officers attached to Arklow Garda Station needed an interpreter as Ms Herda has very little English. Sources say she was in a "hysterical state" and was brought to Loughlinstown for treatment.
Meanwhile, the garda sub aqua team began searching for Mr Orsos's body but the dangerous sea conditions caused the search to be temporarily called off.
As a specialist crane was lifting the car from the freezing waters, Mr Orsos's body was found around two miles south at a scenic beach known as Clogga Strand.
A post mortem was due to take place today.
His brother Zoltan Sandro was immediately driven to the scene by gardai and identified Mr Orsos's body on the beach.
After receiving treatment in hospital, Ms Herda was brought to Arklow Garda Station.
Zoltan Sandro told the Herald that his brother had been in love with Marta.
Csaba and Marta both worked at the BrookLodge Hotel near Aughrim, where manager Pavel Sosnowski said they were "concerned and shocked" at how the car believed to belong to Marta ended up in the water at Arklow.
"We do not want to say anything at this stage, but we are obviously all concerned," he told the Herald.