The "abusing in plain sight" is the thing that men that do this rely on. They rely on women's fear of "making a big scene" or "distracting from the celebratory moment and killing the vibe" to stay silent/not complain.
No, it doesn't even matter if they had dated previously. She didn't want him to kiss her at that moment, and on some level he knew that, and did it anyway, removing her ability to say no.
It's also incredibly selfish. It makes her moment about him.