That's definitely a legit reason to break-up with someone. As you said, social issues are important to you, and how you fall politically on, say, the abortion issue or health care could lead to some pretty fundamental disagreements down the line.

That's not to say that two people from divergent political ideologies can't live in blissful romantic harmony (look at James Carville and Mary Matalin), but it can be a challenge for a long-term relationship. Disagreements may occur over how to raise your kids, how to spend money, what charities or organizations to donate, etc. I have plenty of friends who I don't see eye to eye with on political and social issues. We agree on other things, and usually avoid politics. But when we debate or argue, we don't let it get personal. That's the key to having a healthy relationship with someone whose beliefs-- be they political, social, or religious-- differ from yours. Agreeing to disagree has saved many a friendship and relationship.

But it's good that you're focusing on what's important to you. It will be easier to find the perfect guy if you know what are (and aren't) your dealbreakers. It's tough if everything else is clicking with the guy, but it's also important to stick to your ideals. That said, are you giving the guy's opinions a chance, or are you ruling them out without taking their side into account? If we spent more time listening to each other, instead of just bickering, we wouldn't be in this political quagmire we currently find ourselves in.

Would you date a guy with different political beliefs? If so, how do you make it work?