Not caring?

I'm currently reading this great book called Will Grayson, Will Grayson by John Green & David Levithan. The book basically follows two teenagers both named Will Grayson. They lead seemingly different lives, but are connected by their mutual best friend, Tiny Cooper. Wikipedia explains it better than I do: click here.
Anyway, I'm bringing this up because one of the Will Graysons lives his life somewhat numbly. He refuses to love or become attached to anything. He lives by two rules: don't care too much and shut up. I think by doing this, he thinks he'll become invincible to whatever comes his way, so he'll lead a nice, safe life... but honestly, I disagree. I understand that he doesn't want anyone to be able to hurt him-or notice him, for that matter-but what kind of life is he living if he doesn't allow himself to become passionate about anything? Is he really even living?
Someone I know once said that everyone on the planet wants the same thing: to matter to and be loved by another. And if you don't give out that love, I don't think you should expect to get it from anyone else. If people look at you and see you crying or frowning all day everyday, they aren't going to want to spend time with you. Everyone knows misery loves company, but nobody WANTS to be sad.
I think the point of this post is that, no matter how scary it is, or how much it could potentially hurt, I think you have to love people, and be able to let love in. Because, well, if you don't... what's the point of being here?