We get a just a few direct mentions of "love" in Breakfast at Tiffany's, but it's still pretty important because we are presented with a lot of different ideas about what love really is. There are instances of unconditional love, unrequited love, love between friends, and love in the more traditional sense. And, at some point in the novel, each of these types of love result in pain and sadness. There is no fairy-tale love in this story. Instead, we get a more realistic picture of love – complicated, messy, and sometimes extremely painful.
The characters who fall in love with Holly just fall in love with the idea of her. It's not the real Holly they love.
Joe Bell, Doc, and the narrator really love Holly. In fact, they love her in spite of the persona she constructs for herself.