Not like one's a jock and one's a nerd or any general human/nonhuman or demon/angel twist but something a little more offbeat like Cubism Love (about a girl who after an accident is a brain in a box and her unrequited love for the doctor taking care of her) or Boukyaku no Shirushi to Hime (a princess who has an arranged but happy marriage with a mostly headless king).

How about the soul-wrenching heart-aching agony that is Fujimi Lovers. I highly recommend it, but seriously, I have yet to meet a person that could read it without crying.

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Cynicism at its best.

I'm reading and enjoying both of those right now

I really recommend Mahou Tsukai no Yome. One of my favorite pieces to date. You might also like Yome ga Kore na Monde..

A little different, but still interesting, is Nekota no Koto ga Ki ni Natte Shikatanai. The girl just perceives him as being different, but it's nevertheless a big component of the manga so far.

Tsubame Syndrome is mostly a trashy harem, but

cant remember but it was either in Sumire 16-sai!! or Sumire 17-sai!! where a side character was strangely attracted (or in love) with sumire who is a 16 year old life sized puppet controlled by a middle aged ventriloquist (who never breaks character)