WARNING BEFORE YOU GO ON READING THIS: THIS IS NOT WHAT THE SPOILER SAYS, THIS IS JUST WHAT I THINK IS HAPPINENING
What I got from the full BTS video of the kiss:
Robin is not dead! He is just weak. He encountered a magical being that was sucking out the life out of him or what not. And Regina comes running in telling the monster that if it wants a life, take hers. Then she charges after Robin only to be blocked away by magic. They all join hands and somehow overcome the magic and Regina runs to a weakened Robin then kisses him. It doesn’t look like it’s true love’s kiss because from what I saw, Robin’s eyes were open and Regina was caressing his cheeks before she kissed him. It was like a moment of Regina relishing in the moment that Robin isn’t dead. “Thank god. I thought I lost you.” Then she kisses him and his hands find her arm and he rubs them to comfort her. That’s how I saw things.