Re: Seeing yourself in two places.
I think if you have this much that irritates you about your current boyfriend and find yourself interested in another guy, whether or not you've acted on it, the bf probably isn't the guy for you. Most really great relationships, I've noticed, seem to have periods where things are rough and then they get better, or just minor quirks irritate each other. Like, "honey, pick up your socks" rather than "he is an alcoholic" or "he doesn't respect me." There don't seem to be these huge issues that cause you to wonder if you and your partner really respect each other. I think the fact that you've become a bit interested in someone else is just a clue that you and your bf aren't working.
However, as you already know, definitely make a decision before you dump your bf or hook up with the other guy. I've been in your situation before and just couldn't make a decision and ended up having two guys on my plate... worst idea ever, for everyone involved.