Problem: Continue the following story.

James chose to buy the guitar and leave the piano because that is what he can afford. The 
Here's how I want to continue it: piano is costly.

Problem: Continue the following story.

At the potluck Ian enjoyed their Muendo more than Leslie because 
Here's how I want to continue it: Ian remembered to get butter to put on their bread rolls.

Problem: Continue the following story.

Christopher does not have good willpower, Nelson does therefore 
Here's how I want to continue it:
Christopher ate the cake and increased in size.