What Expectations should I have going into a relationship?

I'm not in one now but I used to have the mindset of wanting to do my best but what expectations should I have about going into a relationship?

That at any given moment someone's heart can change and leave their significant other for another.

None. Expectations suck.

If you're expecting to have time to do other things, then drop that expectance.

Sex is one

To be respected.. maturity but to be honest many people begin relationships as a "Sure we'll see where this goes"