What is the central theme in Death in Venice?

The central theme of Death in Venice is the destructive power of obsessive love. On a trip to Venice, Aschenbach becomes more and more attracted to a fourteen-year-old boy named Tadzio who he sees at his hotel.
Aschenbach is glad when a luggage mixup sends him back to the hotel. Although he becomes aware of a cholera epidemic in Venice, he doesn't care as long as he can be near the boy. He begins to stalk him. Despite Aschenbach's deep obsessive love, he and the boy never speak to each other. Instead, they exchange looks.
Because of his obsession, Acshenbach loses his sense of identity. While he had formerly been repulsed by an older man made up to look younger, he adopts the same strategy in an attempt to be attractive to Tadzio. He also risks his life staying in Venice to be near the boy, and eventually dies of cholera as a result.
The novel raises the question: to what extent should we sacrifice ourselves for an obsession? Is Acshenbach's quest for the purity and beauty, represented by the young boy, noble or is it degrading? The trajectory of the plot critiques the power of illusion and obsession by showing how it destroys Aschenbach, but at the same time leaves us perhaps with an admiration for his dedication to an ideal.