Context

Ready for some moody romance? Look no further than Wuthering Heights.

This quote comes from a young Catherine, as he's explaining to Nelly why she can't marry Heathcliff: he is actually more like her than she is (weird) and it would degrade her to marry him despite her love for him.

Yeah, it doesn't make much sense to us, either.

Unfortunately, Heathcliff only hears the "degrade" part and runs off, only to return much later as a very different man. 

Awkward.

Where you've heard it

Well, this isn't exactly something you'd really say or use, but it is a sort of literary corollary to "opposites attract." It's their sameness that scares Catherine away from Heathcliff—they were raised like brother and sister, after all.

Catherine is more attracted to Linton because their souls are "as different as moonbeam from lightening"...which sounds to us more like a euphemistic breakup line than a reason to marry someone—but real life isn't Wuthering Heights.

Pretentious Factor

If you were to drop this quote at a dinner party, would you get an in-unison "awww" or would everyone roll their eyes and never invite you back? Here it is, on a scale of 1-10.

Why are you quoting Brontë exactly? It's all a bit hyperbolic, don't you think?