He wrapped his arms around the blond's small frame. Fiyero knew that PROBABLY this wasn't helpful BUT what was he supposed to do? Just pretend that they never had something. He knew Galinda well enough to know that would be even MORE hurtful to her.
"I missed you too." He returned the kiss hesistantly, knowing he wasn't exactly lying. He did miss her, don't get him wrong, but...not like that. None of his feelings for her were "like that". Good thing he was a reasonable actor....good enough to fool her.
He wasn't being a bad guy, as awful as this looked, leading on this poor woman. He just didn't know exactly how to handle the situation at hand. Being in a strange place with a former copy of your ex-fiancee is not an every day occurance.