Yeah, you're being paranoid. To begin with, it's easily explained that the friends knew where the friend lived and drove them there, and your boyfriend wasn't paying attention as they drove home. The few times I've ever been driven home when I was drunk, I really was not paying any attention to where we were.
While ridiculous, the oddest explanations are most often the real ones- and just because you think your logic dictates x "should happen", that has nothing to do with reality. Take the fact that he was dropped off 1/2 mile past his own house. For some reason, you think that's weird/suspect. Well, that doesn't mean it is- it just means you've decided it is. Anyone's logic, and reality, are hardly the same thing in any case.
