The Long Island Marine who was among three Americans killed in Afghanistan by a roadside bomb was “the perfect son” who “never ever gave up” – and was proud to be serving his country, his devastated parents told The Post Wednesday.

“I am the proudest dad on Earth,” said Erik Hendriks, the father of 25-year-old Marine Cpl. Robert Hendriks, as he wept over the phone two days after his son was slain.

“It is going to sound like a cliche but he was the perfect son,” said the grieving dad. “He never caused me one problem.”

Hendriks and two other Marines — hero FDNY firefighter Christopher Slutman, 43, and Sgt. Benjamin Hines, 31, of York, Pa. — were killed Monday when an improvised explosive device went off near Bagram Airfield, a US military base north of Kabul.

Hendriks of Locust Valley had just turned 25 on March 4 and was slated to return home within the next two months, his family said.

He joined the Marines shortly after graduating Locust Valley High School in 2012 and his younger brother, Joseph, 24, followed in his footsteps after graduating from the same high school in 2013.

Both of the brothers got their orders to deploy in May 2018 within months of each other – something both wanted to do from the day they joined, their heartbroken mother Felicia Arculeo told The Post.

Now, Joseph Hendriks is escorting his brother’s body home, something the mom said is gift the US military was able to provide.

“As a parent in the wake of such a tragedy losing my child in combat, the one thing I thank God and the Marine Corp. for is getting my son Joseph to where he needed to be to take his brother home,” she said.

Arculeo recalled how on Monday evening a knock on the door came “that no parent should ever have to hear.”

“We are inconsolable and broken into a million pieces,” Arculeo said.

She remembered her son, who she called “Robby,” as “tough” and “hard-working” and someone who “never ever gave up and had a huge heart.

“He was kind and compassionate and was always there for everyone,” she said “That was my son, my hero.”

And she couldn’t be more appreciative of the work her son set out to do.

“I am and always will be proud to call my sons United States Marines,” she said.

The three Marines killed Monday were assigned to the 25th Marine Regiment, Fourth Marine Division in the Marine Forces Reserve, the Department of Defense said.

They were conducting combat operations in the Parwan province of Afghanistan when they died.

Additional reporting by Larry Celona