I have not understood the usage of the phrase "just as .. so" yet.
When should I use it ? What is it meant for ? 

Do the sentences have to be diferent in some way ? 


  "Just as Roni wanted to see her again, so Bony wanted to see him"


There is no a difference between Roni and Bony. Both Roni and Bony wanted to see each other – 


Question: What is an adjective for "requires a lot of work"?
Answer: In terms of relationships, the word for “requires a lot of work” is needy, meaning  “Desiring constant affirmation, lacking in self confidence”.  Wiktionary gives  the following example sentence:


  It's emotionally exhausting to be around her because she's so needy.