Relationship?

What is it to have a relationship? I keep asking people and no one has ever given me a concrete answer.

Where I am right now, the one I'm dating and I have started questioning about the conventions of this world. Mostly it's him but his words have made me think. Would the status of becoming "us" change a lot of things between us?

We're living separate lives but there's something in between us. The thing is, we do not define where we are based on how the usual relationship goes. Although we can talk about it on our own terms.

Whatever the case, are there essentials on what could be called a relationship?