So I was in Riften, then I decided to leave. I go to the gate but..when I activate it, doors open, screen fades to black for loading screen then. Nothing. Loading screen never comes up, and disc just spins for minutes.

Load up save game, same thing (i had just saved before leaving so I lost no time) but it does this everytime now 3 times in a row.

maybe try to fast travel somewhere close??

Just don't leave. Duh!