At first, Dean never planned to confess to you. But the more he saw the love in yours eyes, the love that you refrained from expressing, he realized that eventually it would be too late. Eventually one of you guys would die on a hunt and would have to go on with feelings unsaid.
He knew you needed someone, everyone needed someone.
So, he decided to suck it up and just confess to you, and he couldn’t deny the smirk that grew at the mixture of the two emotions joy and relief that appeared in your face.
Which led to now.. Sam was out getting some groceries for the bunker as you and Dean in bed, his head resting on your lap as he relished in the feeling of your fingers gliding through his hair.
Dean laid there contently knowing that you were his, all his.