You and Dean had been hunting together since the beginning. He called you after his dad disappeared all this years ago. You had been close with him ever since.
You and Dean had a very on and off relationship. It was rocky, to say the least. But you two just couldn't resist each other. Once Dean got the Mark of Cain, he didn't think he'd be around much longer, so he proposed to you. You said yes, but in a way, Dean had been correct. Metatron would end up killing him.
But, of course, the Mark didn't allow Dean to die. Not fully, at least. He became a demon and ran off for months. After a while, you and Sam caught him so you could make him human again. But he didn't want to be human. So, during the process, he escaped the bunkers panic room whilst Sam and Cas were out, leaving you alone with the blood thirsty demon.
At some point, he caught you and had you against a wall in a choke hold, a cocky smirk playing at his lips. That was until you grabbed his wrist with both hands, and he noticed the engagement ring still on your finger after over a year...