Should I Look for Similarities or Differences When I Choose a Spouse?

I’ve been asked what to look for when choosing a spouse. Which relationship is likely to last longer, one with someone similar to me (same race, culture, language, education, hobbies, lifestyle) or someone different?
The answer has a lot to do with Expectations and how well you handle them. The more alike you two are, the more your expectations about marriage will turn out to be valid. Every expectation is a premeditated resentment, a chance to feel let down, a chance to blame someone else for whatever needs or dreams of yours don’t get met. But you might luck out if the other person grew up exposed to the same influences you did. That worked out for me and my first husband for our first 11 years together. And then we hit some circumstances that brought out our differences. And we had no skills to deal with them.
After my first husband died, I learned a lot, especially about how to make sure my needs and dreams get handled with or without a relationship. I discovered how to rely on a husband for what he’s good at and what makes him feel loving, instead of relying on him for everything I’ve ever seen a friend or TV character do for their spouse or the things I’d happily do for my spouse. So, when I married again, I chose someone of similar intelligence and a blue-collar upbringing like mine, but otherwise radically different from me.
Our marriage takes some effort. We both acknowledge that if we’d met in our twenties, we would never have survived even our first date. But we were in our forties, and we knew we had the skills to work through those disagreements and differing expectations. We knew that if our marriage was disappointing, it was because we showed up expecting something in particular, not just love in whatever forms it takes. The surprising result for both of us was discovering so many new angles to love, so many unexpected blessings, and so many new interests to discover. We’re well passed the 11-year mark now and going strong.
But the answer is this: choose someone you don’t want to change. And if you want to keep growing, choose someone with enough differences to lead you to new things.