Ryan Reynolds fell for his wife Blake Lively while they were on a double date with other people. He recounted the story to People as part of an interview in conjunction with SiriusXM. 

Not surprisingly, Reynolds said it really sucked for the other two people on the double date:

About a year after Green Lantern had come and gone and we were both single we went on a double date – she was on a date with another guy and I was on a date with another girl – and it was like the most awkward date for the respective parties because we were just like fireworks coming across.

Sources: People