1 / 7A woman has gone viral after she claims to have caught her boyfriend cheating on her in a selfie he sent.2 / 7Sydney Kinsch had been with her partner for four years, but discovered he had been unfaithful after spotting a reflection of another woman in the photo.3 / 7Uploading a video to TikTok, Sydney can be seen in front of a photo of a man wearing sunglasses.4 / 7As the video moves, she then points to the reflection in his sunglasses, which shows a woman's legs on the passenger's side.5 / 7In the comments of the video, Sydney went on to claim that her ex had been cheating for a whole month before she found out.6 / 7She captioned the video: 'Check the reflection in your boyfriend's sunnies ladies.'7 / 7The video has been liked more than 170k times since it was uploaded two days ago, with hundreds of people praising her detective skills. “Love it when this happens,” someone said, while another wrote: “OMG wow!”When one woman asked: 'Ok but what did you respond I need to know.'