My OH and myself are very much into politics and agree wholeheartedly on everything fortunately. I can't imagine what would happen if we didn't but it's a marriage based lots of other things so I can't imagine there being either of us would leave if this was not so. It would just be a matter of shouting at each other instead of the TV on Thursday night at 10.45 on BBC1.
I'm having enough difficulty imagining how people reach the decision to marry without first finding out their intended partner's general philosophy on life (out of which their politics can, at least, be guessed at, if they don't tumble out, into the open, spontaneously) that I cannot begin to deal with the nub of the question.
Or you could regard the above as an oblique reply.