Prince Harry is set to undertake a series of solo engagements in the United States and the United Kingdom, fueling speculation about his and Meghan Markle's future plans both as a couple and as individuals. The Duke of Sussex's upcoming appearances mark a notable period during which the usually inseparable pair are spending time apart.

This week, Prince Harry begins a slate of high-profile events in New York City. He is scheduled to collaborate with an African conservation group, engage with a youth charity named after his mother, Princess Diana, and support the Halo Trust, a landmine clearance organization that was close to the late Princess's heart.

Next Monday, the Duke will host the WellChild Awards in London, celebrating the resilience of seriously ill children and the dedication of those who support them. This will be his second solo visit to the U.K. in recent weeks, following his attendance at a memorial service for his great-uncle, Lord Robert Fellowes.

At a recent charity polo event in California, Prince Harry appeared without Meghan Markle after the Duchess reportedly withdrew due to illness. The couple, who have frequently appeared together at public events since their marriage, have been spending more time apart following the Duke's recent trip with friends to celebrate his 40th birthday.

"Rumors Harry and Meghan's marriage is in crisis have been rife since he went on his 'lads' holiday' for his 40th, and these solo trips only serve to confirm it," a source told RadarOnline. "Him heading off alone is not a sign of a couple that is inseparable."

Royal commentator Phil Dampier observed the significance of Prince Harry's independent engagements. "It is significant that he is doing so much on his own now," Mr. Dampier told The Sun. "They are living more separate lives as it looks like Harry is trying to carve out what exactly his future is. I suspect Harry has been feeling very much like a spare part. He wants more fulfilling roles for himself so we may well be seeing more of him here."

In a statement released ahead of his birthday, Prince Harry expressed affection for his children, Archie, five, and Lilibet, three, describing them as "kind and funny." The statement did not mention Meghan, which some observers found noteworthy.

Speculation about the couple's time apart has been addressed by various sources. "Harry is feeling more and more isolated in California, which is why he has been reconnecting with old friends back home," a source told The Sun. "He wants to carve out a way back into royal life back in the U.K. and is seeking counsel from old friends and associates."

However, official statements from the Duke and Duchess have not indicated any change in their relationship. Representatives for the couple have not commented on the rumors, and there is no confirmation of any marital issues.

Meghan Markle has not accompanied Prince Harry on his recent trips to the U.K., and reports suggest she prefers to remain in California. Meanwhile, Prince Harry's increased solo appearances have led to discussions about his future roles and involvement with charitable organizations.

Buckingham Palace recently addressed a separate issue, denying claims that Meghan was cropped out of a photograph used in birthday wishes from the Prince and Princess of Wales to Prince Harry. The Palace stated that no intentional exclusion occurred.

As Prince Harry continues his solo engagements, royal observers are keenly watching for indications of his and Meghan's future plans. His involvement with causes close to his heart, such as conservation and children's charities, remains a significant focus of his public work.

The Duke's upcoming appearances underscore his ongoing commitment to philanthropy and may signal a new phase in his public life. Whether these independent ventures indicate a shift in the couple's joint endeavors remains to be seen.