By that logic, every person you date you expect to marry. When it’s over, see if there’s anything you should’ve done differently, see if you learned something about yourself, or see if your former significant other just taught you something about others. People change over time and that’s not necessarily a bad thing. But, if I’m changing to the left and you’re changing to the right, then we’re growing further apart and eventually we can’t see the middle anymore. Long-lasting relationships happen when both people change and they happen to be changing toward the center. They get closer and they stay together. I never enter a relationship expecting to meet in the middle. But if it happens, I’m down to hang out in the center for as long as we’re both comfortable there.