The monarchy has set rules for the Royal Family since day one. In Prince Harry's case, his wife Meghan Markle also set a rule for him but -- but he broke it in the end. As they say, some promises are made to be broken. 

The royal couple faced issues on privacy and even had legal battles with the press. But recently, they faced a more personal matter when the Duke of Sussex was caught drinking alcohol.

During Prince Harry's visit to Japan to support the England rugby team, he was spotted holding a bottle of beer even when Markle already forbade him from drinking alcohol.

The Duchess of Sussex herself was health-conscious, too, and she tried to persuade her husband to do the same thing. The Duke of Sussex was reported to have said okay with the set-up "to show his solidarity" to a then-pregnant Meghan.

Markle set the rule after they found out that they were expecting a baby. Put simply, she wants Prince Harry to have a healthier lifestyle.

According to royal commentator Neil Sean during his talk with "The Today Show", Prince Harry broke the rule and was seen guzzling a bottle when he traveled in Japan alone. He also personally witnessed the younger brother of Prince William carrying a bottle of beer.

"I saw him holding, let me tell you, a bottle of beer so I don't know how that's going to go when he gets home to Meghan. Apparently, he doesn't drink anymore, as all boys say," Sean told "The Today Show".

Because of this, the royal commentator was led to believe that the Duke was confronted by the Duchess when he got home.

Despite this one-time breaking of rules, an insider secretly praised Prince Harry for keeping his promise that long and congratulated him for somehow making it and coming around to healthier living.

"Considering he's been a pretty brutal drinker since he was a young teen, it's quite an achievement," the source told Express.

The insider revealed that like his wife, Prince Harry also engages in yoga while eating healthy foods and doing exercises.

The Rule Lives On

The rule is set to continue now that Prince Harry and Markle recently showed their intention of having a second baby.

When the royal couple visited military families in Windsor, the Duke of Sussex started asking a question about how it feels like to have a second child.

One of the mothers at the Windsor event, Susie Stringfellow, told Forces Network that since Archie's age is close to their babies, Prince Harry got interested in asking how it is to have a second child. In the end, the mothers encourage the royal couple to finally have a second child.

READ MORE: Prince Harry Proves Loyalty To Meghan Markle In The Cutest Way Possible [VIDEO]