Notes: A very short Spones whatsit for you all.
Disclaimer: I do not own Star Trek 2009 and I make no profit from this work.
First off, the telepathy thing. McCoy was no fool - any Vulcan relationship would be heavily reliant upon that telepathy of theirs, and no thank you. Telepathy was not McCoy's cup of tea. Being in a relationship with someone that could read his thoughts at the drop of a hat was not the most appealing prospect in the world. Some things - some thoughts - were not meant to be shared, least of all with your significant other.
Follow that right up with the Vulcan bond. McCoy knew about marriage bonds - or at least what Starfleet Medical had told him - and if he didn't want to share every last thought with his spouse, why would he want said spouse to be able to tell where he was and what he was doing all the time? That was just asking for trouble - McCoy had had a wife, so he would know.
Vulcan monogamy was another thing. Now that wasn't especially linked to Vulcans, per se, but more McCoy himself. He wasn't proud of it, and God forbid he admitted to anyone - but he was the reason for his marriage collapsing. One drunk night after yet another fight, one pretty girl in the wrong bar, and he'd driven the final nail into the coffin of their marriage. He had hated himself for it - still did - and swore blind that he'd never do such a thing again.
Only he'd sworn blind that he wouldn't do it the first time around either - gotten up in front of his family and friends and in-laws-to-be-in-about-half-a-minute and sworn in front of God that he wouldn't do such a thing. And he had.
It just wasn't worth the risk.
New Vulcan was no less atmospherically pleasant than Vulcan. Enough said.
The in-law. McCoy had met Spock's father, and quite frankly, he was torn between scared shitless and wanting to punch the impassive bastard in the face. He didn't like Vulcans and their attitudes on the whole, but Sarek just got his goat. Sarek just pissed him right off. And frankly, he would have to be dragged kicking and screaming into any family that contained Sarek, son of Skon, son of who-the-fuck-ever.
"Because I do, in fact, love you, Leonard."