Problem: How does the sentence end?

Erin was always trying to follow Sarah's correct grammar, because 
Answer: Sarah was controlling and anal retentive.

Problem: How does the sentence end?

Betty but not Victoria had to go for a screening because 
Answer: Betty noticed an unusual growth behind their ear.

Problem: How does the sentence end?

Elena got very good grades in school while Lindsey was constantly failing classes because 
Answer: Lindsey did not have very good study habits.

Problem: How does the sentence end?

Aaron really like dogs but Derrick is allergic to them. 
Answer:
Aaron petted the cute puppy.