I close my eyes and I see, blood and roses.

Yeah, a little morbid, and it is pop, but it always struck me as being memorable.

And though it is not a single line, I also like:

I had to stop in my tracks for fear of walking on the mines I'd laid, and if I built this fortess around your heart. Encircled you with fences and barbed wire. Then let me build a bridge, for I cannot fill the chasm. Let me set the battlements on fire.