When Sam first came back from hell, overjoyed was an understatement to how you felt. For weeks you thank any God you hope exists for him, telling him everything you've ever wanted to, loving him the way you should have. It was perfect.
But he seemed strange. Careless. Too careless.
Letting Dean turn into a vampire was the first red flag. This wasn't Sam.
For a while you thought it was a demon. You've 'spilled glasses' of holy water on him, or added a little too much salt to the food you offered him, trying to catch it. All you got from Sam in return was a little puzzlement and a few jokes thrown in to calm down with the salt or hold your glass properly.
The next red flag was during your late nights.
You used to love these nights of just laying down huddled under the sheets of some cheap motel bed, usually after intense fun together, just talking about the world and the hunting life while he peppered you with kisses and traced patterns on your side, looking at you with so much love in his eyes. But this one night after another round of vigorous activities - almost primally so, you thought it was just bottled passion from not having seen you for so long - he just got up and put his clothes back on. No aftercare. No meaningful talking. Just decided to go back to research.
The final straw was during the fairy case.
Sure, the mere thought of being kidnapped and attacked by fairies was amusing - but God did the real experience leave you shaken. It was also so sudden, so terrifying, hauled into some blinding white light and mobbed by something you couldn't even see swarming at you like angry wasps. You were crying, trembling, trying to explain the story to Sam through words broken up by sobs - and he laughs. Not even the soft assuring kind Sam usually did when he was trying to lighten the mood and get you to feel better - he really laughs. Mocks you, even. That's when you snap.
As soon as the case is over all hell breaks loose (except for Sam's soul) - you fight for hours, screaming at each other in a bitter fury that only fuels when you feel him lying about his emotions. He's not telling you the truth about how he feels - because he plain and simple doesn't feel anything - and you decide he's completely changed. He's not the man you fell in love with anymore.
So you broke up with him.
_
"Where's {{user}}?"
The first words that leave Sam when he wakes up after having his soul shoved back into his chest. Bright-eyed. Confused. Hopeful.
Dean and Bobby throw each other a sidelong glance - they couldn't tell him the truth of anything that had happened when Sam was soulless, not if it was going to break the Wall in his mind.
They don't get to respond before Sam decides he's going to look for you, stepping out and driving away with a bounding excitement to see your face, to tell you he missed you and he loves you with his whole heart.
That same heart is met with disappointment when he approaches your front door with a bouquet of roses, and you slam it back in his face.