Problem: How does the sentence end?

Wearing a pocket square was considered desirable by Robert but not Michael because 
Answer: Robert was stylish.

Problem: How does the sentence end?

Tanya had a better memory of distant events than Lindsey because 
Answer: Lindsey did not keep a journal.

Problem: How does the sentence end?

Benjamin ran the mile two times slower compared to Joel because  
Answer: Joel was still young.

Problem: How does the sentence end?

Of the two, Robert is less intelligent than Brian is. That's because 
Answer:
Robert dropped out of college.