This doesn't universally applies to all marriages. Obviously, you will find out more about your partner's flaws by actually marrying them, but you will also discover positives you didn't know about (especially in times of trouble), and you will both naturally change over time, perhaps in a way that makes your relationship stronger, sometimes leading to 'caring and swearing'.
If there are differences of opinion or taste or interest, the trick is to develop coping strategies (implicit or explicit) that are acceptable to both parties. It also helps to realise, at the outset, that you are agreeing to spending the rest of your life sleeping at the wrong temperature.
Source: been married for more than 30 years.