Thanks for the responses, still have to read through them all.
Breakfast In Bed wrote:
I'd actually say it's vastly underrated, and it's one of the traps of waiting until marriage. It will eat at the relationship if you both aren't compatible and both of you aren't getting what you want (or feeling emotionally forced to get what you don't want).
Worst case scenarios, one person can only do a sprint session, the other wants a marathon; one person wants to be pegged the other has rape fantasies; both might as well lay still because they're so uncoordinated. Any others you can think of? Which variable affects compatibility the most? I would go with the psychological.