Meghan Markle and Prince Harry marked their third-year anniversary as a couple. But instead of celebrating the milestone, the Duke and Duchess of Sussex should be very careful.

On the “Royals” podcast, royal expert Angela Mollard said that the third-year mark of the royal couple’s relationship is crucial.

“I’ve been thinking about this a lot because three years is generally understood by relationship psychologists and counselors to be the point where you move out of the limerence phase. Limerence is deeper than infatuation, but it’s the beginning of a relationship where it’s all butterflies and you laugh together all the time and you’re very amenable… Three years is around the stage where reality starts to kick in,” she said.

The royal expert went on to say that Prince Harry and Markle’s relationship has moved very quickly by necessity because shortly after tying the knot, they welcomed their son Archie. The Duke and Duchess of Sussex also took a completely different approach from the Cambridges.

“It’s that transition phase, to real life, with a baby, with the pressure of your jobs. There are a lot of conflicting forces in their lives… I think they have to have a marriage that is stronger than most… And, I think that’s going to be very, very hard… They will have to work very hard with a lot of pressures that most people don’t endure, to make sure that they focus on their relationship staying really strong,” Mollard said.

The royal commentator concluded that she hopes the royal couple will receive all the support and guidance that they need to navigate through their relationship. After all, Markle has been vocal about the struggles of her and Prince Harry’s marriage.

During her previous conversation with Pharrell Williams, the “Suits” alum said that “they” don’t make things easy. As of late, it is still unclear if she was talking about the public or the press.

Meghan Markle Prince Harry The Duchess and Duke of Sussex are pictured on Jan. 14, 2019, in Birkenhead, United Kingdom. Photo: Danny Lawson/WPA Pool/Getty Images