There isn't really any solution to avoiding a broken heart. Even marrying the first person you ever loved, there will be some level of heartbreak even after marriage.
Then there's the times you fall in love with someone who was never more than a friend – yet you both wanted it to go further. Those times when you fall in love so fast you barely have time to blink before you realize you disagree wildly and vehemently on just a few issues, yet those few being some of the biggest marriage dealbreakers one can have.
And you wonder, “Should I stay and hold on, or just walk away?” “Should I pray for his mind to be changed, or just assume that's a useless endeavor?”
You talk, and talk, and debate, and discuss. You push and pull and hope beyond hope that they will see the error of their beliefs, or that your errors will be revealed.
Yet after a few months, you realize it just won't work. A load of bricks drops on your hopes, your dreams.
Why? Why, Lord? Why bring the potential perfect spouse, yet it's someone I could never marry?
Then it ends, just as quickly as it began, one broken heart more and one best friend less. What could you have done differently, how could you have avoided it all?
The sad and incredibly true answer is that... you couldn't have. Feelings already spiraling out of control even before the pertinent issues were discussed – on the 4th day of the friendship. It was crazy, and terrible, and fun and heartbreaking.
So, moral of the story, kids! Try not to fall in love with someone who you disagree with on incredibly important doctrinal issues. :P