The actor sparked interest after sharing this cosy snap with his The Greatest Showman co-star Rebecca Ferguson.
"A pic is worth a thousand words. Only ones I can think of now are: wtf were u thinking dude?! Look at her!!" he wrote with this image of the pair on set.
He followed up with the sweetest Tweet the world has ever seen, sharing a photo of himself staring into the eyes of Rebecca during a press event for the film.
"I finally looked...😍 #GreatestShowman" he wrote.
The love-heart eye emoji? The looking into her eyes? We're practically swooning!
For those unfamiliar with her work, Rebecca is a 34-year-old Swedish actress, who has starred in major films including Girl On The Train and Mission Impossible: Rogue Nation. Neither Zac or Rebecca have confirmed the reports they are an item, though we're obsessed with the idea.
Despite the lack of confirmation, fans are convinced that this means the duo are an official item now and they were quick to react on Twitter. See some of the most hilarious reactions below.