Everyone knows the golden rule for when attending a wedding - never upstage the bride. Picture: PxHere

Everyone knows the golden rule for when attending a wedding - never upstage the bride. In this case, the bride was left in tears after one of her wedding guests arrived wearing a designer dress.

According to Yahoo Lifestyle, the guest in question took to Reddit, asking: “Am I The A*****e for wearing an expensive designer dress to my best friend's wedding?”

The unnamed woman explained that she had rented a designer dress for the big day because she had nothing fancy to wear. According to her, she thought the only restriction was not for other guests to wear white.

“So I wore a rented off-the-shoulder red gown. I also had my makeup and hair professionally done because I'm inept at personal styling,” she wrote. 

The bride, who also happened to be her best friend, opted for a $100 (about R1 500) charity wedding gown for her day. 

“When I showed up to the wedding with my husband, who wore a tuxedo, there were audible murmurs. Immediately, it was clear that we had overdressed. Most women were in plain dresses and most men were wearing normal suits,” she said.

Her wedding attire obviously didn't go down well with the bride, who approached her friend afterwards in a flood of tears. “She told me that just because I had a perfect life with a wealthy husband and that I had kept my figure, etc. etc. didn't mean I had to upstage her on her own wedding day,” the woman added.

Reddit users seemed divided on the subject.

“This is her best friend and she had no idea it wasn't black tie? Oh wait, except she did know and she also knew she was dressing more formally than the bride, her best friend,” one user commented.

“I don't think you did anything wrong as you weren't purposely trying to upstage anyone, unless you knew it was going to be low key at the time," said another.