Actually Kalidas, you bring up another reality check to this question.
For example, i stated I am a Hindu and I would only marry a Hindu (and am sure glad I did!).
But there are some who were already married, let us say both were Buddhists when they married but then after the marriage the wife realizes she is actually a Hindu, and even more specific a Krishna Gaudiya. So in this example they were the same religion when they were married, but then after marriage they were not. I do not think a Buddhist husband would then turn away from his wife or visa versa. Nor do I think they should, the marriage is that important and should be maintained.
And also, yes, there are some religions, though not the same, that get along admirably when they marry - I would go back to the Hindu - Buddhist example, they easily can be side by side.
So while, personally, I would only marry a Hindu, I can see mixed religions in marriages that work out fine.
Not all mixed religions, but some.
Om Namah Sivaya