When does the dating end and the relationship begin?

I wasn't entirely sure which category this should fit in, but I believe that 'relationship' should fit in health. What with all the health issues that follow heartbreaks.

Now, the basics:
Dating: go out with (someone with whom one is romantically or sexually interested).
Relationship: an emotional and sexual association between two people.

A lot of people would say that it stops and starts at when you say ‘I love you’ to each other, some would say, it’s the moment you both decide to be exclusive and some would say it’s when you move in together. Those aren’t the only three instances, I’m sure, and there is never really a clear answer. I guess it depends on you.

But, wait a minute, it should depend on both of you. Shouldn’t it?

Maybe you welcome that notion, but what about him/her? Do you ask? Do you look out for the signs? Is there a code? Even if you did, does that mean you’re getting married? And if it does, are you really sure you want to get married now?

Where and how can we get that perfect time frame between matrimonial bliss and dating?

Note: You don't necessarily need to choose from the pole. I wish there was an option where everyone can add their own answers for others to vote on too.