confusing..what does "long distance for long time may create conflicts between couples" mean?why why not say "separating for a long time may create conflicts between couples?

I feel confusing .What should i do confusing..what does long distance for long time may create conflicts between couples mean?why why not say separating for a long time may create conflicts between couples? How does that work?This piano thing is so confusing What does she like? what does Bob do? What does your mother What time does school what does she do? What does tom do? what does friday do What does she do? what does chinese mean What does it mean What does she work? What does sam what does she doing? What does Miss Green what does this mean?