Chemistry vs. common interests in romance novels

[Roni Gehlke]

Do you believe that a featured couple in a romance should have something in common so that they show they will have a lasting relationship after the story has ended or is it only important to show that the couple have a chemistry between them now?

[sari]

Chemistry is a very important to me but, I do feel the couple should have something in common so the reader understands why they fell for each other. Deep down Rhett Butler was a better person than Scarlet O'Hara, but he does understand her and can be as callous as her so the relationship works.
On the other hand I have yet to figure out why self poised Edward fell for whiny self hating Bella.