Adam took pity on her, walking over to give her a hug before saying, "It's alright. You owe it to yourself."
The 26-year-old gave his blessing to Cartier's new relationship, effectively allowing himself to be eliminated from the show.
"I'm not going to get in the way of that," he added afterwards, appearing to tear up as well.
He also told Carter she was "one of the nicest girls" he'd ever met.
"If I had my time again, I would do exactly the same over. Like, look, I love yous all (sic)," he said.
And it appears the feeling is mutual. A visibly tearful Matthew later told Sophie:
"My best mate gets dumped, that sucks... but it's going to be worth it."
Following her romance with Gerard Majda, Cartier dated Adam for four weeks until they decided to be friends.
The lifeguard has since moved on with Matthew.
Love Island Australia continues Monday at 8.30pm on Channel 9.