According to Franklin Habit there is a gauge curse:
"Swearing in front of witnesses that you never swatch because you never need to will curse you with seven years of incorrect gauge."
You can read about his other lesser known curses here.
However it's a well known knitting myth that knitting a sweater for a significant other before marriage can lead to the relationship breaking up. There is even an old Ravelry group testing the curse. You can find it here. There's another group for believers of the curse here.
The belief in this curse is so pervasive there is a Wikipedia page here. That page does give some interesting alternative explanations for the myth.
The good news is the Ravelry groups are pretty much inactive, perhaps it proves the myth hasn't happened enough for much posting.
Has it happened to me you ask? Unfortunately yes! Do I believe the myth? No, but then I'm not really the superstitious type. I did knit my husband a few sweaters in the early days of our marriage only to realize he just doesn't wear sweaters. We will be celebrating our 25th anniversary next Christmas eve.