RocknRolla
Gerard Butler showed up to set for RocknRolla sick with a cold. His costar, Thandie Newton, refused to kiss him. Why should she risk herself getting sick for some kiss? She told Director Guy Ritchie that and they ended up reconfiguring the scene. It ended up working out way better than expected!
The Vampire Diaries
Nina Dobrev and Ian Somerhalder broke up right in the middle of filming The Vampire Diaries. After they broke up, the two refused to do kissing scenes. They somehow managed to pull off the epic love story between Damon and Elena without the kissing.