We might just be jumping to too many conclusions. Maybe the dance is before they tell him that Vedika didn't plan anything. These promos are always misleading.
Also, I think i get Ram's behaviour, as in why he barely has a reaction to finding out that Priya hasn't planned anything. I think Ram is fed up, fed up of feeling abandoned, feeling like he's not loved, like no one cares. All the villains around him have made him think that Priya doesn't care. He's probably so devastated, that he's closed off his mind to any logical suggestions or statements. He just doesn't care. Maybe once someone tells him a second time, that Priya planned it, like we know Sara does when bringing out the cake, thats when it will click. How he's been really rude to Priya, and has broken her heart because of what he's done.