I think he wanted gud for Sunny only . Actually Sunny told shonali about whom did she vote...while sky was unaware of the conversation b/w them n thought that sunny must have voted amar..When sky came to know about it it was too late n by the time shonali n sunny had already interacted. So now he thought of loosing amar at his side...so he wanted to do damage control n told shonali about sunny not voting for her. BUT then He soon realized that its not gud to lie even if it is game n felt bad for Sunny as she was portrayed as lier...So he did his best to convince shonali n eventually he told amar the truth which shows that he is not bad at heart...So it was big misunderstanding... IF sunny haven't told shonali at first place this won't have happened...BUT saying that he fooled/ cheated sunny is not possibility at all , it was just misunderstanding which got clarified at the end .