Meghan Markle appeared visibly emotional and on edge alongside Prince Harry in Brussels Tuesday — just days after her estranged father, Thomas Markle Sr., was arrested on child porn charges.

“Meghan’s eyes look weary, with noticeable dark circles and a subdued expression,” body language expert Susan Constantine exclusively told Page Six.

“Her usual bright-eyed smile, the radiant smile that seems to light up a room, appears dimmed amid the current news surrounding allegations of a sexual nature involving her father.”

Constantine believes the Duchess of Sussex appeared to be doing everything she could to “hold herself together.”

“Yet the sadness in her eyes, the tension across her face, and her dimpled, slightly pouted chin seem to tell a different story,” Constantine said. “She maintains her composure and puts on a brave face for the cameras, but a visible heaviness lingers in her expression.

“It almost appears as though she is fighting back tears, determined not to let her emotions overwhelm her in public.”

While Markle, 45, and her husband, 42, were physically present, Constantine observed that their body language showed they didn’t seem to be in joyful spirits.

“The couple appears on high alert as they scan the cameras and spectators around them,” she said. “They maintain a steady pace, seemingly aware of the attention on them.”

The Duke of Sussex seemed particularly “concerned” with his surroundings, the “How to Spot a Liar in 7 Seconds or Less” author said.

“The repeated stroking of his beard, coupled with his serious countenance, gives the impression of someone deep in thought and perhaps unsettled by the circumstances,” Constantine said.

The Sussexes’ rep did not immediately respond to Page Six’s request for comment.

Harry and Markle unveiled the Lost Screen Memorial installation in Belgium’s capital Tuesday. They were seen holding hands before Harry gave a speech about how children “deserve to feel safe” while using technology.

Markle, who was initially scheduled to speak as well, stayed silent after reports surfaced that she wasn’t emotionally “strong enough” following her dad’s arrest last Friday for allegedly possessing child pornography. He has denied the allegations.

Page Six exclusively confirmed that the Sussexes would not be addressing the arrest.

After news broke that Thomas Sr. was under investigation, Markle said she was “deeply distressed” by the allegations, which she had allegedly known about for years.

Meanwhile, Harry’s estranged brother, Prince William, attended Remembrance Day events with Kate Middleton Sunday — just days after Thomas was charged.

Constantine noted that Middleton appeared as she usually does, “bright, cheerful, fully engaged and authentic to her core.”

“She clearly enjoys people and has a natural gift for establishing rapport through her warm, engaging smile and direct, sincere interest in those she meets,” she said.

By contrast, Constantine believes William displayed interest through a more animated expression.

“With slightly raised eyebrows and a downward gaze that seems to accompany a polite response,” she said. “His facial expressions can sometimes come across as a little comical or awkward when engaging with others, but in an endearing rather than negative way.”

Constantine cautioned not to read too much into their expressions, saying a still photo can be “misleading.”

As for Markle Sr., he is back in custody and had his pretrial release revoked Tuesday after allegedly cutting off his ankle monitor, Page Six exclusively reported.