5 reasons Jim is in love with Pam:
She laughs at his humor: It's wasn't until after high school, someone laughed with him, not at him, and Pam was only the 2nd person to get him. He loves how when she laughs he doesn't feel like a nerd anymore.
She never dresses up: It's been fun to see her in the same sweater everyday. He loves when she adds color to her wardrobe though, it makes him feel like she's dressing up for him
She participates in his plots: It's always more fun when she helps. He loves how she makes his plans better, he feels like they complete each other.
She doesn't stand up for herself: It's been a while since she told Roy no, and even though it kills him each time she dose give in, he loves how he wants to save her from him
She doesn't love him back: It's been a blessing and a curse. It kills his heart that she doesn't, but his head loves how he wants to sweep her off her feet. It's a sick game his emotions play on him, but he loves her non-the less.