You shouldn't get involved romantically with your friend's partner.
Jackson is hanging out with his best friend's girlfriend Lindsey when Lindsey starts flirting with him.
Jackson doesn't want to hurt Lindsey.
Jackson brings up  memories with his best friend and Lindsey while resting his hand on Lindsey's shoulder.
Jackson flirts with Lindsey getting into a relationship with her.
Jackson is thanked by Lindsey who realizes that she lover her boyfriend.
Jackson loses his friendship when he best friend catches him with Lindsey.