It's something most couples will experience, unfortunately. In my experience it's usually the girl who meets a guy who she has "so much in common with and feels a real connection, and he GETS me".
I'm gonna serve this one up as I see it, but as usual there's a disclaimer - I'm pretty bitter right now.
Okay, you are getting kind of bored with your boyfriend and have found someone else who will give you a lot of attention. To qualify your interest in other guys, you've been thinking about your boyfriend in more negative terms - angry, stubborn, arrogant (even though you will try to avoid guilt from this by still saying he's a "great" guy).
Ultimately, either this guy, or the next one WILL make a move on you, and you might be okay going along with it because in your mind your boyfriend is such a scumbag. Afterwards, you might think along the lines of "our relationship had ended ages ago when you started treating me like crap", or "what did you expect me to do when I couldn't even engage with you emotionally!?".
I really hope I'm wrong because this kind of thing breaks my heart - it's often the first signal of a slow and painful break-up for the poor boyfriend. On a plus note, you'll be fine - you'll have plenty of guys who are "interested" in you after you separate.
Talking to other people is great - friends are crucial, but when you start asking these kinds of questions you should know there's a huge problem. Either you're happy talking to this guy as solely a friend and are totally comfortable in your relationship (you're apparently not or these thoughts wouldn't have occurred), or you're thinking about going off with other guys and it feels like your relationship is holding you back.
Man, that was pretty bitter. But I'm serious. I've been the boyfriend in these kinds of relationships a few times and it's utterly soul-crushing.