Gorgeous Zac, 26, was asked if he's off the dating market during an interview on ITV's Good Morning Britain, broadcast on Tuesday morning (29 April).
A coy Zac replied: "I don't know. I'm not really sure I'm in the market…. I'm not investing!"
Oh, Zac, keeping us guessing!
Zac stars alongside Halston in brand new movie Bad Neighbours, and the rumoured couple were pictured posing together (alongside the rest of their colleagues, we must add!) at last night's Los Angeles premiere.
While neither Zac nor Halston have addressed the dating speculation, a source told E! News this month: "They are definitely an item... Her friends love him and say he is so sweet. He's really good to her."
Although Zac stayed quiet on his love life, he did admit during this morning's interview that all is good in his life and he's looking forward to the future.
"I'm just super excited about the future man, this has been a long time coming and I was a kid when I started doing this [acting], I never thought I'd have the chance to work with Seth [Rogen on Bad Neighbours] so I'm pinching myself I'm still around."
Bad Neighbours hits UK cinemas on 3 May.
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Watch a trailer for Zac's new movie below: