If you spend your whole dating career making decisions based on “following your heart”, what are you going to do after you get married and you and your spouse go into a [temporary] funk (because it’s going to happen), and your “heart” tells you your in love with someone else?
Are you still going to follow your heart then? Does your heart supersede your vows? Then why bother even making them?
No. You’ve got to figure out how to base your decisions outside of something as fickle as your heart.
And trust me, you want to figure this out before you get married.