Well... if I'm dating casually, I'd always use a rubber when having sex. Then I don't have to worry if the guy is being honest with me or not.
But when the double-standard it put in play... "Corri, you be exclusive with me... and I'm telling you that I'm exclusive with you... but I'm going to see what I can get away with..."
THAT is the problem. Especially during dating... because it is dating...
