The guy I'm dating is a great guy, but he's drastically small and all of my body contortions just don't cut it anymore. Sex is occurring less and less and he still thinks it's amazing (when we have it). I on the other hand am totally bored and feel like a pencil is jabbing me. Am I wrong to dump an amazingly sweet, nice, generous guy over his "I just hit puberty" looking penis? I still have a great time with him, but am repulsed by him sexually now and at this point I find myself getting drunk around him just to get aroused. Should I just keep a "real" man on the side?
Secondly, just because your boyfriend is bad at fucking doesn't mean you have to hate on the small-dicked. They take a lot of shit from a lot of people, and they would like you all to know that many of them excel at fucking. People in the know will tell you: do not dismiss the small-dicked.
But, reader, back to your question. Is it "wrong" to break up with him because you are literally repulsed by his lovemaking and get drunk to endure it? Er, I'm going to say no. Ladies, gentlemen, you have my permission to break up with whomever you please, but most especially people you find repugnant.
The reason you're wanting to break up with him isn't his small dick, though, it's the fact that you don't like how he fucks you. You, too, bear some of the responsibility for this predicament, madam. Everybody's got different fuck parts, and everybody likes different things done to and with their fuck parts. How on earth does anybody know what the right thing to do to anyone else is? Here's a hint: it is basically the answer to every single sex problem ever.
TALK TO YOUR PARTNER!!! TELL HIM WHAT YOU WANT! FOR FUCK'S SAKE PEOPLE!!!! If you are "totally bored" and "feel like a pencil is jabbing you" while fucking, YOU ARE DOING IT WRONG. It's not 1820, you don't have to just lie back and take it any more. Also, you're not doing him any favors by letting him think he's doing a great job, only to have you hating every second, contemplating either dumping him or getting some side action.
Say: "Sugarbutt, let's try some oral." Or: "Honeyballs, I really like it when you fingerbang me until I come first." Or even: "Loveytaint, this isn't working for me. Let's explore our options." Pro tip: dude probably is not unaware that his dick is small. Work with him to find a way for both of you to get off awesome.
Or don't! I mean, I'm not saying it's your moral responsibility to fuck this guy, and from what you're saying, it sounds like maybe you're too far along in hating him to reverse. But folks, if you don't like the sex you're having, and you haven't said anything to your partner about it, then that bad sex is partially your fault.