Love is in the eye of the beholder or at least it appears that way. You could think of it in terms as one person's junk is another person's treasure. In terms of a novel, when do you decide if you love it or not?
Is it after you catch a glimpse of the cover art and title? Is it after you read the brief, hooking paragraph on the back cover? After the first 3 chapters? Or when you finish the book having either laughed aloud, sobbed through the last 20 pages, or yelled at the main character for being an idiot?
I would say in all my years of reading, the words, "I love this!", come after the finale- never before. I have to read all the pages to know if the book really has me hooked. The cover and title may be interesting, the back cover catching, the first 3 chapters alluring, but the end tells me if the whole experience was worth my money.
This philosophy is present with the music I choose to listen to, the movies I watch, and the other forms of media I submit myself to devoting time to.
For those who decide the fate of something prior to the end miss the magic, romance, or horror that unfolds in the middle and the revelations at the end.
The phrase, "A rose by any other name would smell as sweet", has no meaning if you have never read Romeo and Juliet.
To truly love something you have to experience the entirety not just a little tidbit.