The Angel of Thursday loves the Righteous Man
Dean is still asleep when Cas takes in how beautiful he is. Its the only time he can, when Dean is awake he grumbles something about personal space and Cas backs off. But asleep Cas watches over the righteous man and maybe just maybe counts the freckles on his face. And when he is done he counts them again and wonders if Dean will ever notice the way Cas stares at him. Or if Dean will wonder why Cas is so flustered when he is around. Cas wonders what it would be like for Dean to love as much as Cas loved Dean. The second Castiel touched Dean's soul he knew he loved the man. Castiel wished and wondered what an, as Dean calls it, 'apple pie life' would be like with Dean. He wishes for humanity to live and grow old with Dean Winchester. He keeps these thoughts to nighttime only however, he doesn't Sam or Dean to notice. He doesn't want to lose their friendship. So he doesn't tell.
The Righteous Man loves The Angel of Thursday
Dean hates himself for loving Cas. Perfect always flustered Cas. In fact at night Dean often dreamed of his angel. Dreamed of putting his lips against his angel's. Dreamed of the day he would stop this life of hunting the things that go bump in the night for Cas. He dreamed of living in a big house, having kids and growing old with Cas. But Cas is still an angel and he deserves so much more than what Dean can offer. Dean will never tell Cas he needs him too much. If Cas were to be disgusted by Dean's love and left him, Dean might kill himself. So he doesn't tell.