I Love Trouble
In the 1994 movie I Love Trouble, Julia Roberts and Nick Nolte had a horrible relationship. In fact, their bickering and fighting got so bad that they began to film their scenes in separate rooms. No one was excited about that kiss in the end, which was less than remarkable.
Six Degrees of Separation
Will Smith is a committed actor... nowadays. Not so much back when he was filming Six Degrees of Separation. Despite the fact that this character is gay, Smith refused to kiss a man. He made them film the scene from behind so he could fake it. The director, Fred Schepisi, was less than pleased with the drama he incited onset due to one kiss.