Thomas Rees was shopping in Sainsbury's in Hackney, London, on Monday when a security guard approached him and his boyfriend to say someone had complained about them holding hands, he told BuzzFeed News.
The 32-year-old said he had just finished paying for his shopping at the Hackney Road store when he and his boyfriend Josh were "beckoned over" by the guard.
At first he thought they had accidentally stolen something, "because we were made to feel like criminals".
"My boyfriend and I became aware we were being watched," Rees said. "We were holding hands, arms around each other's waists, basically showing public displays of affection.
"As we came to pay for our shopping I noticed a security guard watching us. Once we had paid, he then approached us and asked us to follow him outside."
Rees said the security guard told them a customer had complained about the couple. The guard said that while he "was brought up to believe in live and let live", he had to tell them the customer had said they were touching and behaving inappropriately.
Rees said he did not witness the complaint being made and was "stunned and shaking". "I just don't understand why he needed to take us outside and why he needed to tell us," he said.
"There was no sense of humility. I refuse to believe this would have happened to a heterosexual couple – we just stared in disbelief. The issue here is it felt like like 1960s Britain."
Rees tweeted about the incident on Monday.
And people responded with support for the couple.
Rees said the guard acted inappropriately in deciding to pull them aside and that Sainsbury's should ensure staff are fully trained to deal with diversity.
He now feels uncomfortable shopping in the local store for fear of seeing the guard or discovering other customers in the store who share the same views as the complainant.
"The sad thing is there are multiple situations when Josh and I are holding hands and I'm the first to push him away," he said, "but I felt safe surrounded by my community and I was oblivious and unguarded."
He was torn over whether to complain, he said, but "part of me thought I should raise my voice".
A customer service representative had since offered Rees a £10 gift card to apologise, he said, but he felt the gesture was not enough and Sainsbury's should instead ensure all staff are properly trained.
This is not the first time the supermarket has found itself embroiled in controversy over its treatment of same-sex couples.
In 2014, campaigners staged a "kiss-in" at a Sainsbury's store in Brighton in support of LGBTQ rights after a security guard allegedly asked a lesbian couple to leave a store for kissing. At the time the retailer apologised and said: "This should never have happened."
A spokesperson told BuzzFeed News on Tuesday: “We do not tolerate discrimination in any form. We are investigating this urgently with our security contractor."