Hane Glass no Kimi.

This Gothic shojo manga is a single volume comprising three stories—a main one, "One with the Glass Wings," and two shorter stories "Firefly" and "Jion Princess"—that feature characters falling in and out of love, against all odds. There is a fragility to the main characters in each story; each is afflicted with some sort of physical and/or mental ailment—for instance, a blood disease is the affliction in the main story. But regardless of all the obstacles and interference, love conquers all.