It sounds like if you are thinking of someone else then perhaps you don't have strong enough feelings for your current boyfriend. I suggest you think about whether you truly love your current boyfriend. Be honest with yourself. If the answer is no then it's best for both of you to break it off. Don't compare your current boyfriend to this other guy.
You obviously don't like your boyfriend that much if you fell for the other guy. Maybe you should get to know this other guy that you like before you jump to conclusions. Go out with your boyfriend a little more. See if you really do still like him or if your really hooked onto this other guy.
Totally normal. Sometimes girls like other guys when they are dating someone. If you really think that the other guy would make you happier than the one you have now then go for it. But don't break your boyfriends heart and immediately go to the other one. Take your time. Figure it out. It always ends well. :) Hope this helps!