Simon loves Kaylee.
(Well, he's comfortable with her, which is near enough, he supposes.)
He's decided he's going to marry her one day.
(Because with life so unstable, unsafe, uncertain, it's nice to have that certainty, that she's his and he is hers.)
He wants to be with her forever and everyone, everyone on Serenity knows that.
(That doesn't stop him from realizing that every time he feels really alive, he's with River, hushed moments of illicit kisses and touches in quiet corners that leave his heart racing, his head pounding.)
Love, he decides, is safety; River is something else.