Good relationships also take skills, such as: romance, understanding your spouse's point of view and what matters to them, maintaining the right equlibrum of intimacy and independence, being reliable, clearly expressing your own needs and making it emotionally safe for your partner to express theirs, conflict resolution, facing unpleasant truths, teamwork, respecting consent not just in sex, sexual communication, compromising on life plans, attachment style, staying mentally healthy, keeping the magic alive, etc.

You can probably test for those skills. I'm curious how.

Of course, you also need compatibility. But I have a hunch that's both overrated and easier to check for on a date.