Karlie Kloss and her boyfriend, Joshua Kushner, are going strong after five years together. Could an engagement be on the way?

Kloss and Kushner, 31, have managed to keep their longtime romance out of the spotlight for years. Though the low-key couple attends the occasional red carpet event together, they’re often just spotted walking around New York City. In fact, their romance is so mellow that some people didn’t even know the supermodel had a boyfriend! But that doesn’t mean the pair isn’t serious.

The 24-year-old recently took to her Instagram to wish her man happy birthday and put her love on full display. “Happy birthday to my best friend and partner in crime,” she wrote. “The past 5 years of our adventures together have been some of the best memories of my life. I love you @joshuakushner.” She added a sweet poem by @atticuspoetry writing, “My atoms love your atoms. It's chemistry.”

Karlie Kloss, Joshua Kushner Married Soon? Karlie Kloss and Joshua Kushner have always kept their relationship low-key (photo: Splash News).

The Victoria's Secret model usually keeps mum about her beau, who is Jared Kushner's brother, the son-in-law to President Donald Trump. She did open up to OK magazine recently, though. “I was definitely not planning on falling in love,” the fashion maven said. “But I think that's the thing about it, you can't anticipate or plan it.”

On their four-year anniversary, Kloss gushed about how she “met my best friend” adding “I love you more every day.” She also told InStyle magazine how they work hard to manage their busy schedules. "You make it work,” she said. “We've been together almost five years. Time flies. It's crazy. He's a super-solid dude."

Will Josh Kushner Propose To Karlie Kloss In 2017? Will Josh Kushner propose to Karlie Kloss in 2017? (photo: Splash News)

Kushner, whose family are well-known real estate moguls in New York City, is much quieter when it comes to discussing his girlfriend. He seldom gives interviews, but his Instagram account is filled with uncaptioned photos of Kloss from all over the world.

So is a proposal on the horizon? Sources have claimed that they’re “not interested in marriage anytime soon.” They both have packed schedules, and Kloss is only 24.

Do you think Karlie Kloss and Joshua Kushner are a good match? Let us know your take in the comments section below!