People seem to fall in love with brands for three reasons that work together:

1. Desire: Maslow’s hierarchy of needs sums it up best; a theory in psychology, proposed by Abraham Maslow in his 1943 paper A Theory of Human Motivation, which organizes basic needs such as food and shelter at the base of a pyramid and aspirational needs (self-actualization) at the top.*  No matter what level of the pyramid your product or service works on, it has to fullfil a need in order for people to fall in love with it. I actually think the word “desire” is more accurate than “need”, but either way a motivational force is essential because it’s pretty hard to make people fall in love if they don’t want to.
2. Trust: In the diagram below, the brand experience stairway illustrates how brands build trust through interactions and over time. I’ve written about this in my post Where Marketers Are Today, but the gist of it is that satisfying customers’ desires/needs/motivations repeatedly leads to beneficial behavioral patterns and ultimately to trust. Actually, you can even go beyond trust to loyalty, but the underlying idea is that people don’t fall in love without establishing a behavioral pattern.
3. Emotional Connection: First off, falling in love is not rational, does not obey economic theory, and is not simply based on a Pavlovian satisfaction of needs. Second, there are degrees of being in love, and you can fall out of love if you don’t acknowledge/appreciate the sentiment.  It’s really a cocktail of satisfaction, behavioral pattern, and disposition. In other words, you can do everything right and some people just won’t ever fall in love with you. It’s sad, I know, but there are lots of fish in the sea who will fall for your brand if you’ve got desire and trust. The trick to getting people to fall head over heals is to let them have what they love. Give them the brand.

*Chip Conley wrote an interesting book about how to apply Maslow’s hierarchy to business called Peak: How Great Companies Get Their Mojo from Maslow. Here’s a great video of him presenting on the topic: