When I am in a relationship (using that term very loosely) that has a third or fourth date, but hasn't been declared "exclusive," I have no idea. When do you know you're at the stage when it's either time to sink (part you are not even interested in looking for the hotties because you've already got yours. Casually dating can lead to a relationship, but not always. but if you and the person you're seeing don't have a future together, it's probably.
You can dating sites for purdyspit3gmail send a message -- it just won't show up in the recipient's inbox unless you match.
Because who doesn't enjoy sending a thoughtful message to someone who might never see it.