MAGUIRE: I ask you about love, y'probably quote me a sonnet. But you've never looked at a woman and been totally vulnerable... known someone that could level you with her eyes.
It doesn't take long for Maguire to see through Will's childish mind games, no matter how clever they are. He knows that Will has experienced all of life through the books in his tiny apartment. But he also knows that Will doesn't have firsthand knowledge of the world because he's too scared to take risks with his heart.
MAGUIRE: And you wouldn't know what it's like to be her angel, to have that love for her be there forever. Through anything. Through cancer.
Maguire knows that Will is a lot smarter than he is, but he also knows he has something that Will doesn't: the true experience of loving someone and being totally out of control. He knows that Will has never dealt with watching someone he loves die of cancer, and that gives Maguire an advantage in his efforts to help Will open up.
MAGUIRE: You don't know about real loss, because that only occurs when you love something more than you love yourself. I doubt you've ever dared to love anybody that much.
Maguire makes a good point when he says that Will doesn't know real loss because he's never let himself love someone enough to be devastated by losing them. And in this sense, he's never really lived. Because in Maguire's view, feeling real loss is one of the things that makes us fully human.
SKYLAR: Look, um... If you don't love me, you should tell me because it's such a—
Skylar loves Will a lot, and before they go any further together she needs to know if he loves her back. Even though he keeps pushing her away, she won't leave him alone unless he looks her in the eye and says he doesn't love her.
SKYLAR: You're afraid of me. You're afraid that I won't love you back. And you know what? I'm afraid too.
Skylar knows that Will is afraid of their love because he thinks it will hurt him in the end. But she's willing to admit that she's scared too. After all, love is scary. Anything that can hurt you that badly is scary.
SKYLAR: I love you. I wanna hear you say that you don't love me. Because if you say that, then I won't call you, and I won't be in your life...
The only way Skylar will get out of Will's life is if he says he doesn't love her. Otherwise, she'll think that he's just scared and she'll keep trying to help him through it.
WILL: I don't love you.
When he's finally confronted by Skylar about whether he loves her, Will stares deep into her eyes and tells her he doesn't. This is crushing for Skylar, and we know that this is still Will's fear and weakness overcoming him. He still hasn't learned enough to open up and let himself be vulnerable with someone else.
SKYLAR: I love you… Will?
Even after Will has told her he doesn't love her, Skylar keeps telling him she loves him. She knows that Will is trying to push her away, but part of her must think that he'll open up if she keeps pressing her love on him.
MAGUIRE: I don't regret the eighteen years I was married to Nancy. I don't regret the six years I had to give up counseling when she got sick. And I don't regret the last years when she got really sick. And I sure as hell don't regret missin' the damn game.
To help make a point with Will, Maguire tells the story of how he missed one of the biggest baseball games ever to hang out with the woman who would become his future wife. Will can't believe he'd miss such a big event for a girl, but Maguire tells him that this is the whole point of life. He feels a ton of pain for losing Nancy. But he doesn't regret a single moment he ever spent with her.
WILL: Sean, if the Professor calls about that job, just tell him, sorry, I had to go see about a girl.
At the end of the movie, Will seems to embrace the things Maguire has taught him. Instead of taking a high-paying and prestigious job, he drives off to California to see Skylar. In this sense, he has finally made a decision that's right for him and his emotional future. It doesn't mean he's always going to be all right. It doesn't even mean that things will work out with Skylar. But what it does mean is that Will has gotten over his fear and is ready to embrace the uncertainty of love.