The post got fans very exciting, urging for Chandler, 22, to propose to the young wildlife fanatic. Other fans even wondered if he had already popped the question!
Chandler left a loving response to the photo, writing, "This made my entire day. I love you so much. Thank you for being the kindest most amazing girl a guy could ask for."
"Pop the question Chandler!!!" wrote a fan, with another commenting, "PUT A RING ON IT, CHANDLER."
Another fan wrote: "Am I the only one who gets excited every time they post thinking it's an engagement."
But the couple have made it quite clear that they are in no rush to marry, despite calling each other 'the one'.
In December, they posed for PEOPLE magazines cover, addressing engagement rumours at the time.
"For us at the moment, I think it's just been about enjoying life."
Chandler, the American wakeboarder, added: "It's really great just to slow down and enjoy the ride."
The couple first met at Australia Zoo in 2013. Together, they now work hard at carrying on Bindi's father Steve Irwin's legacy.
Just last week, Bindi's brother Robert Irwin posted emotional throwback photo tribute to his father on social media.
The 15-year-old shared a split image of two photos— the late Crocodile Hunter and himself feeding a massive croc in the SAME spot.
"Dad and me feeding Murray... same place, same croc - two photos 15 years apart ❤️🐊," he captioned the photo.