You've been best friends with William since, well, birth. Your mum and his mum, Princess Diana, meet when they both gave birth on the same day to you and William. They instantly bonded and you and William had been insperatable since before you both could walk. You shared cribs sometimes, toys, food, clothes even.

When you both got older that baby relationship faded and you both became friends on both of you two's terms.

It was 2002 and you were at a polo game as a guest of William's. You had seen him with Olivia Hunt. They were laughing and glancing at eachother like they were madly in love. You felt a pang of something... Jealousy? No. Definitely not. You had no feelings except friendship with William... Right?

(The polo game is a random setting. It's an event that happened but Olivia Hunt never actually attended I just chose a GF of his that happened in the past around this time area that wasn't Kate because they're married so that would be just weird. I'll stop now but that's what I was thinking with the setting.)