Gabriel knew something was off when he couldn't feel Sam anymore, but he ignored it, and focused on the man on top of him, but to Sam, everything crashed down around him, and he was left alone in the rubble, with his broken heart turning black and bleeding out in front of him. He started driving, and didn't stop until caffeine wouldn't work anymore and he was forced to sleep. When he woke up, there were over a hundred messages on the phones that were in the glove box. At least he remembered to disable the GPS trackers on them. He stayed away for almost a month before he actually got the nerve to end his life. He knew what he had to do.
He let out a deep breath as he walked into the woods. He carried a duffle bag on his shoulder as he walked. He'd left all of the clothes he had when he bolted away from Gabriel and Dean. He walked until he was lost, then sat on the ground, setting the bag in front of him and looking at what was inside, tears running down his face as he remembered.
For the first two weeks, Gabriel had looked everywhere he thought Sam would go. He didn't think Sam would have that reaction. He'd cried for a couple of hours when Sam was with the bitch. It was only after he searched, going out of his mind that he stopped to think about it. He thought about the way Sam had been acting for a couple months before. He refused to take off his clothes, which meant their sex life came to a screeching halt. He was distant, guarded, and he just seemed kind of off. He'd put up mental blocks, so Gabriel couldn't get into his head, but Gabriel didn't realize those things were connected until he stepped back, and looked at it from a new angle. When he pieced it all together it was too late. Sam was gone, and he'd blocked himself from being found.
When Gabriel realized what was different, what had changed, he cried for days, and was violent. Sam had depression, and Gabriel didn't even drop his emotional walls long enough to see it. He didn't try to fix it, because he was too selfish to see something was wrong. What he did, was the worst thing he could have possibly done. He ripped away everything that could have helped Sam. He realized all that, and he cried, because he knew he might never get Sam back.
But the real problem was, he would have a one in a million chance to fix everything he broke. He might never get to save Sam.