They thought no one was looking.

Tyler Doyle was caught on camera popping the question to his girlfriend, Cristina Acuna, in a Seattle park on Valentine’s Day -- but the couple didn’t know it at the time.

A random tourist snapped the exact moment Acuna said yes before he had to rush off to board his bus.

Now, after the photographer launched an online appeal to find the couple, the two parties have been brought together.

A Reddit user who goes by the name serg82 was visiting Seattle’s Kerry Park as part of a tour group when he saw a man on bended knee proposing to his girlfriend. He whipped out his camera and captured the scene.

Speaking to Q13 Fox, ‘serg82’ said: “The tour bus was about to leave, and I was the last person to get on board.”

He posted the image on Reddit, which quickly went viral, and the story was picked by Q13 Fox.

It didn’t take long for Acuna to see it.  She contacted the Fox station to say that the picture was of her and her now fiancé Doyle –and described the magical moment.

“I had no idea what he was doing but I was just like ‘okay he’s acting so weird whatever,’" she said.

After working up the courage to pop the question, Doyle kissed Acuna  --and that’s when the picture was taken.

“Now we’re happy and ready to [take the] next step,” said Doyle.

The couple has a photo to mark the big moment --thanks to the kindness of a stranger.