Even though He's Just Not That Into You was a particularly average film based on a supposedly hilarious(I haven't read it yet) book of the same name, I think it has basic glaring truth. Why are we trying so hard to make excuses for the people in our lives?
We enter into any alliance based on an idea of what we want that relationship to account for in our lives - whether a source of approval, or fun, or ego boosting, or advice/wisdom, whatever. So then we've already made up our minds about what it and the person who brings it is supposed to be like. And no matter what the person does or says contrary to it, we'll search desperately for the smallest and even most superficial way for it to fit into our 'idea' of what we ache for him/her to be like, effectively pulling the wool over our own eyes.
How do you remedy it. Needing, not loving, is the most severe hobble you could walk into a relationship with. You come to a point where you, your family, your friends, your pets, your books are all you'll ever need. It's when you'll be perfectly ready to be in a relationship that is lucid, honest and minus the bullshit.
It sounds a bit cold and clinical - why be in a relationship when you are wanting for nothing from said person? So you don't have your blinders on. You see the person for what he/she really is - deep haunting voids, small kindnesses, loveliness, awfulness - in all their glory and you feel free to lose yourself in deep love with this person, completely unfettered by imagined ideas of how this person can complete you.
In the end you choose, you don't let your weaknesses choose for you.