I think because people were shipping them for a long time, it felt like they were an established couple whilst in reality they had only been back together one day. And in that recoupling, Ekin chose Davide, so even though he acknowledged he was glad she had 'picked him up', he hadn't chosen her so them being in a couple was of her making. I feel Ekin really hurt Davide, hence his OTT anger towards her. Even after their date things weren't fully resolved and he wasn't completely open to her, then Casa happened.
He knew Ekin would find out about anything that happened at Casa, so whilst there might have been an element of exploring, (though there wasn't any great interest shown by Davide), perhaps it was more to do with a bit of pay back. I think it had the added benefit of helping to focus his feelings as he realised other girls can't compare to Ekin, so we will see a new warmer more romantic relationship now, at least that's what I'm hoping for them.