Your assuming everyone who votes for a person shares all that candidate's beliefs.
It's a free country and you can choose to like or date whoever you want. If politics are a deal breaker for you then that's your perogative, nothing wrong with that. But I do agree with Damo in that it seems you try to draw this one line down the middle and your either on the right side or the wrong side (kind of like Bush does).
But if you believe with all of your heart that policy effects people, and being on the "wrong side" means the deaths of thousands, and in war time, hundreds of thousands?
Then it becomes a little tougher doesn't it.