My million dollar question.
Just because he heard from Anchal and Sambhavna that this BR leela acts is looking cheap on TV then ONLY he confronted Diandra saying, TUM hug karti ho, TUM open ho..TUM yeh sab kiss karti ho...achcha nahi lagta...we are "JUST FRIENDS".
Pehle to HERO ne khoob maze liye and he was absolutely fine with all those PDA; Kissing, touching, cuddling...more to add... and not to forget those lipstick ke nishaan which the Hero thought was an "Achievement in Olympics". Now, when he was told by the outsiders how he is being potrayed to the outer world..he got a panic attck and every blame was put on Diandra.
I like, how you being a GG fan atleast noticed and came up with the clear state of mind stating that he has been wrong and acted like a jerk.