Now a source tells New Idea that Robert, 16, is reportedly having a hard time and is feeling stuck in his big sister’s shadow.
“Robert is starting to get really fed up with everything being about Bindi at the moment,” says the insider.
“He’s sick and tired of Bindi getting all the attention and him being the forgotten little brother. He feels like everyone always pushes him to the side and forgets he’s there.”
The insider adds: “It’s been happening all his life and he’s just over it.”
It must be unfamiliar territory for the Irwins, who are such a tight-knit family, living and working in very close proximity and constantly showing their support for each other on social media.
Until wedding guests were limited under the new government precautions, Robert was set to walk his sister down the aisle in front of family and friends, and had told Access Hollywood it “meant everything” that Bindi had asked him to step in for their late dad, Steve.
Earlier in March, Bindi, 21, showed off the flowers she’d chosen for the event in a post to social media and asked her followers to give her any wedding tips and advice.
Days later, Robert posted a throwback clip of himself and Chandler, 23, singing, and wrote a touching caption about how his future brother-in-law was his “lip sync buddy”.
He added: “soon you and Bindi are getting married, wow!!!! There’s no one more perfect for Bindi and I’m so happy for you both!
It’s also believed that Robert is very unhappy that his girlfriend, Elisha Jackson, hasn’t yet been welcomed into the family as Chandler has been.
“Robert also feels like no-one is giving his girlfriend a chance,” the insider continues.
“Everyone accepted Chandler straight away and welcomed him into the family with open arms, but he just doesn’t feel like his girlfriend has been treated the same way.”
“He’s starting to act out overit all, and Terri had to sithim down and have a chat with him. He’s very ambitious and wants his time to shine. Terri knows she has to tread carefully with him.”
Robert and Elisha are said to have connected on Instagram after Elisha, who admitted to having a crush on Robert for some time, visited Australia Zoo.
She then shared a picture from her day out, along with the caption: “Yesterday I went to Australia Zoo and told @robertirwinphotography how I felt.”
The pair were later spotted enjoying lunch on a double date with Bindi and Chandler.
For more, see this week's New Idea - out now!