“I think if you do go out with someone for quite a long time you do get to know each other very, very well...You go through the good times, you go through the bad times, both personally and within a relationship as well.”
— Kate Middleton
Simplified Meaning:
When you spend a lot of time dating someone, you really get to understand them deeply. You experience both happy and sad moments together, in your personal life and in the relationship.