A few of you have probably figured it out by now, but my version of Caramel is not exactly emotionally healthy. I'd like to explain why now.
Mostly, it relates back to his "special talent", if it could really be called that: he's unlucky. Really unlucky. To be honest, about the only "good" thing that's happened to him in his life recently is Big Macintosh showing an interest in him.
His job is not something he particularly likes; he takes a good deal of satisfaction from doing it well, but to him it's a job, not a calling. Everything around him will break or be damaged somehow, and often it's because of his own actions. If there's anything that can go wrong in his life, it will. Murphy's Law isn't something that he uses to shrug off a minor mishap, it's the principle that guides his life.
And he has a sister, who's the polar opposite. She knows what consequences are; they're just never bad ones. Caramel's parents, love him as they did... well... you have two children, one who literally can do no wrong, and the other who could step outside and cause a forty pony pileup. Whether you try to fight it or not, that will start to wear on you.
Caramel's sister has had nothing really denied to her, ever. She's had her cake and eaten it too, for her entire life, and the end result is a filly who really doesn't see other ponies as ponies, just moving backdrop that gives her things. It's telling that she only gets angry when her brother has something she doesn't, and it's something that she can't seem to have. I didn't intend to write her as such a heartless character at first, but after some thought with how her upbringing would have made her, it was inevitable.
I admit, though, I wasn't expecting the final result to be an evil version of Rarity.
Caramel, on the other hand... his life is a never-ending parade of stuff going wrong. He's used to it. It's what happens to him. And he just bows his head and keeps on trudging along, because that's what he does. It's more of a shock to him when something goes his way, because that never happens. He's so used to the worst possible situation developing that it's what he's always bracing himself for, and should it not happen, he literally does not know how to react. He's also extremely passive about it; his life sucks, he's used to it, but since there's no way to change it as far as he knows, why bother?
And yes, he is sabotaging his relationship with Mac, intentionally or otherwise.