He’s a doof. Like your stereotypical country boy, manly-man, boy-next-door kind of doof; who thinks that his stories from home are funny (they aren’t) and that she needs an escort at night to protect her (she doesn’t), who always laughs a tiny bit longer than is polite at her dumbest jokes and calls her mother “ma’am.” But she can’t keep the grin away even when he’s being particularly obtuse, can’t stop her eyes from shining with affection even when his own friends are mocking him for how…silly he gets. And she knows he keeps it up just to see her laugh as she joins in.
He’s earnest, a picture-perfect Boy Scout, so good that she sometimes feels guilty that she’s corrupting him from his original purpose in Sunnydale (the military part, not the evil-demon-making part). He asks for directions when they get lost because he’s more respectful of her time than stubborn. He kisses her goodbye on the cheek every time he leaves until she finally pulls him to her and tells him (with liberal tongue) that she doesn’t mind something more. He won’t enter her until their eyes have met and she’s mired in pools of love.
He tries desperately to fit in in ways that her last boyfriend never did (could?). He lets Dawn fiddle with his gun just to win her over and even agrees to paint her nails before Buffy hears them talking and spares him. He’s never exactly just one of the gang, but he still talks to Willow between classes, still gives Xander the guy friend that he so desperately needs. He’s kind of leery around Giles, but he never lets it show to anyone else. She likes to think that she’s the only one who can read him that well, anyway.
He lets her embrace her sexuality in ways she’d almost thought were fiction, after Angel (but she doesn’t think about Angel) and Parker. He’s the last thing she sees at night, the first she sees in the morning, and she’s finally beginning to understand that a relationship can really be this complete, that she can get the whole package- sex, love, joy, friendship- and never lack for any of it. He never hides his want for her once they’re behind closed doors, and he never hides his love for her when they aren’t. He’s unashamedly hers, and it overwhelms her.
He’s hers. That’s the gist of it, isn’t it? She can see undisguised affection every time he looks at her, affection she can’t help but mirror when their eyes meet. And she shudders at the realization of the power that he’s given her over him, the responsibility that she couldn’t cast aside if she wanted to. Which she doesn’t, because all those things about him that she loves? They’re perfect, and he’s perfect, and she’s the luckiest girl in the world to have him. She’s happy to embrace the burden of love he’s given her.
Absolutely, completely, utterly happy. (Except she’s terrified.)