Much hay is made throughout this page about how "stupid" Ray is, but I think the viewer(s) might be missing something. Ray isn't stupid, he just makes two bad assumptions but both are based on lies he is set up to believe. The first is that he assumes it's Abby that killed Marty; but of course that's exactly what Visser was trying to make it look like and why he specifically stole and used her distinctive pearl-handled .38 to kill Marty. The second mistake he makes is that when Abby seemingly doesn't know what he's talking about after having buried Marty, he's interpreting that as her giving him the brush-off. He thinks this because of what Marty bitterly says to him earlier in the film when Ray goes to quit/get fired and Marty is sitting on the steps by the incinerator: Marty tells him that Abby will eventually betray Ray, too, and ditch him for someone new. These words were obviously just Marty saying something petty to try and get a dig in on Ray but they clearly stuck with Ray more than he let on. Ray thinks Abby's genuine confusion is a put-on so that she can throw him under the bus to take the fall for the murder.
Much hay is made throughout this page about how "stupid" Ray is, but I think the viewer(s) might be missing something. Ray isn't stupid, he just makes two bad assumptions but both are based on lies he is set up to believe. The first is that he assumes it's Abby that killed Marty; but of course that's exactly what Visser was trying to make it look like and why he specifically stole and used her distinctive pearl-handled .38 to kill Marty. The second mistake he makes is that when Abby seemingly doesn't know what he's talking about after having buried Marty, he's interpreting that as her giving him the brush-off. He thinks this because of what Marty bitterly says to him earlier in the film when Ray goes to quit/get fired and Marty is sitting on the steps by the incinerator: Marty tells him that Abby will eventually betray Ray, too, and ditch him for someone new. These words were obviously just Marty saying something petty to try and get a dig in on Ray but they clearly stuck with Ray more than he let on. Ray thinks Abby's genuine confusion is a put-on so that she can throw him under the bus to take the fall for the murder.