Jack being arrogant, petulant and one track minded(by this I mean getting ideas and not letting them go). He always did what he wanted, like back in 2009 when he pretended to be romantically interested in Roxy to get more access to Amy, and kind of to spite Ronnie(because she didn't instantly forgive him and take him back after finding out about Amy).
Or when he went after Tanya and played super Dad to Abi and Lauren. Then he pitched a fit when Tanya left him. I think he nearly threw Lauren and Abi out of their house because of it too.
So right now, he's probably enjoying shutting Roxy out, because she doesn't really fit into his ideal family life. I get that he had good reason at first, but his motivations are probably not entirely down to the drugs.
Though typically Jack wasn't that much of an arse unless you crossed him. Getting upset about paint doesn't strike me as that in character, but that's my view. He usually saved his petulance for bigger things.