JIM WATSON via Getty Images U.S. President Donald Trump and first lady Melania Trump board Air Force One in West Palm Beach, Florida, on April 16.

President Trump is at it again.

People on Twitter recently pointed out that the president left his wife, Melania, behind while deplaning Air Force One over the weekend. In one photo, the president is at the bottom of the airplane’s stairs, greeting and saluting people on the ground, while Melania is still descending.

Bastard did it again pic.twitter.com/wAn4TqkiMs — Brasilmagic (@Brasilmagic) April 18, 2017

Many online criticized the distance between the two, pointing to other presidents ― like Barack Obama and Ronald Reagan ― and the way they descended the stairs with their wives.

@Brasilmagic @KaraCalavera @NellSco Compare and contrast with this photo—and there are many others on the web that show the same thing. pic.twitter.com/ZbzW02Nnbg — Carl Maniscalco (@maniscalco_carl) April 18, 2017

@Brasilmagic @pattonoswalt love him or hate him; this is how a gentleman treats his wife. pic.twitter.com/O8oJb8Q2zK — gillwho? (@sarim0t0) April 18, 2017

Whitmore, an international etiquette expert who has appeared in the New York Times and shows like “Fox and Friends,” explained the traditional rule of etiquette when it comes to men and women descending stairs.

“When a man and woman are coming down the stairs the man would go before her. The logic being that if she trips or falls, the man (generally being larger or stronger) would be in a position to catch her,” she told HuffPost. That being said, Whitmore said the president’s distance in these pictures “could be perceived as a sign of disrespect.”

“In the photographs, what we’re clearly seeing is that Donald Trump is walking not just one stair ahead, not two stairs ahead, but a few feet ahead. She’s not being accompanied by him,” Whitmore explained. “If you look at some of the old photos of Ronald and Nancy Reagan or the Obamas, they are very close together. In other words, they’re a unit, they’re a couple, they’re engaging in this activity together.”

Whitmore added, “Whereas in this particular photo, she is clearly standing all by herself. Now it could also be a sign of self-absorption or he’s in a hurry. He’s a role model for the country, having said that –- he should be modeling, I believe, a different kind of behavior.”

Swann, a lifestyle and etiquette expert who has been featured in the New York Times and appeared on the “Today Show,” echoed Whitmore’s take.

“The husband at the bottom of the stairs, saluting and greeting the people there, and the wife is still at the top of the stairs – this is incorrect,” she told HuffPost. “The proper thing for him to do is to wait for his spouse at the bottom of the stairs and then take her hand and assist her down the last few steps as she comes down. This was not done.”

Swann added, “He still is a husband first before a president. Because he’s in the presence of a woman, and this woman is his spouse, he still has to make sure that he’s nurturing his relationship. And part of nurturing your relationship is the small gestures and niceties that are necessary in terms of chivalry.”

During Trump’s inauguration in January, the president was also criticized for not waiting for Melania to get out of the car and then leaving her behind while he greeted the Obamas.

@Brasilmagic I'm going to weep silently now. I cannot express how much I hate Trump and miss decency, manners, sincerity. pic.twitter.com/abuLT2L5Y7 — Rispa Frances (@RispaFrances) April 18, 2017

@Brasilmagic It's sad to see a guy with no social graces. Doesn't know how to treat a lady. It devalues her. She's just luggage. Such a shame. pic.twitter.com/2KrgoV1BxO — Sissiboo Smith (@sissiboo_smith) April 18, 2017

“When I look at the video [from the inauguration], this same thing rings true. President Trump should have never bounded up those steps, leaving his wife behind on the opposite side of the car,” Swann said. “The proper way to go up the stairs is the lady always goes first, and then the gentleman follows behind her – whether you are the President or not.”

Communication and body language expert Susan Constantine might’ve said it best in an interview with Mic after the inauguration.