Kissing is just part of the job for an actor, so even when they dont enjoy it, they have no choice but to get on with it.
Rachel McAdams and Ryan Gosling: The Notebook
This one will break your heart. The couple that we all want to be, actually had a lot of behind the screen tension. However, to make you feel better, once filming finished they clearly got over their differences, as they dated up in real life.