The 7 Trickiest Love Triangles on Grey's Anatomy

This is the most heartbreaking of all the love triangles. While Denny is the love of Izzie's life, he's sadly just a memory. A literal ghost. Unbeknownst to everyone, Izzie's health slowly deteriorates. She accepts that she's having an affair with a hallucination and attempts to live accordingly. It seems that the more Izzie pushes Alex away, the more he wants to support her. This is one of the first times we see Alex caring about someone other than himself.