Mitesh Patel, 37, owned and ran a chemists with his wife Jessica, 34, who was found dead at their home in The Avenue, Linthorpe, Middlesbrough, on May 14.
Jessica was originally from Leeds and her family paid tribute to her at the time of her death.
He denies her murder and is on trial at Teesside Crown Court.
Before they were sworn in, Mr Justice Goss QC told a panel of potential jurors details about the couple.
He said: "Both of them worked as pharmacists and owned and ran the pharmacy on Roman Road in Linthorpe.
"It is agreed that during the course of the marriage, the defendant Mitesh Patel has been unfaithful to his wife including having met men for sexual intercourse, some of whom he met using a social networking site called Grindr."
The judge said customers of their pharmacy or anyone who had used the Grindr app should not sit on the panel.
The judge said the prosecution will open the case on Thursday morning.
Addressing the panel before sending them home for the day, the judge said Mrs Patel was "undoubtedly" murdered and that the defendant said it was not him.
"It's as straightforward as that," he said.
He said the case was serious, adding: "Instinctively, when you hear aspects of the case you may react emotionally.
"You have to put emotions to one side.
"You try the case, dispassionately, coolly, calmly and collectively assessing the evidence."