When you’re dating, you will likely make pronouncements about how you feel about various topics, whether that be parenting, where you want to live, what you want to do with your life, how religious you are or want to be, what side of politics you lean towards, and so on and so forth.
But that doesn’t mean you can’t change your mind one day.
And if you’re in a relationship, that doesn’t mean your partner will have to agree or support your change of heart. Oftentimes you won’t realize how you feel about a certain topic until you’re in the moment when said topic presents itself. You are allowed to change your mind, but if it’s something pretty huge (like deciding you no longer want kids, want to move halfway around the world, or want to become an Orthodox Jew), then you can’t expect a significant other to instantly decide to change their life along with you. Follow your heart’s desire of course, and don’t decide not to change because you’re afraid your partner won’t approve or will break up with you. At the end of the day you have to be true to yourself.
That said, if you’re engaged, married or have children, altering your life drastically may be more of an issue, and it’s important to make major decisions like this as a couple.