But in all the excitement they didn't forget that today is a very special for their niece Princess Charlotte - her fourth birthday.
We imagine the couple have sent Charlotte a lovely present (maybe some slime? Kate said yesterday that her daughter loves the stuff) but they also sent a sweet message on Instagram .
To celebrate the occasion the Duke and Duchess of Cambridge shared three new photos of their daughter, which were shared on the social media plaform.
Meghan and Harry were among the thousands of people who commented on the sweet snap, which was taken by Kate.
They wrote: Happy birthday Charlotte! lots of love, H and M xo" with balloon and birthday cake emojis.
While most people loved the message, others were annoyed they didn't use the word 'princess'.
One wrote: "Even on Kensington Royal (her parents insta) she is referred to as Princess Charlotte. Meghan is just being disrespectful like she was to Prince Louis."
Another commented: "Even if they are related through Harry, she needs to call her Princess if other Royals call her that. This isn't because they're related, it's respect."
One woman wrote: "So why they call her princess? Because it's a sign of respect!! Even Queen's account calls her princess."
Another simply added: "That's Princess Charlotte to you."