I think every break-up I've experienced since I've started shidduch dating has boiled down to that one word.
One time it was Hashkafah, different values. One time it was different attitudes. One time it was different feelings. One time it was differences in perspectives and orientation on life.
Sometimes I wonder if we think the word "bashert" means "similar" or "the same." Same goals, same values, same perspectives, same orientation, same feelings. Same thoughts and actions. Same background and culture. Just sameness -in humor and intelligence, in expectations and desires, in how we approach and what we want out of life.