Saved her life and i feel she thinks?

This is a very sensative topic but I thought some people out there may he able shine some light on this. 2 weeks ago I was walking with a girl who I only realy talk to in college in lessons although we had a bit of a jokey friend ship. Anyway, one day we were crossing the road and a car was coming really fast and she didn't see it, I did so I ran onto the road and tried to grab her but relized I wouldn't make it and so just pushed her, and I got hit. I broke 2 ribs, but its was nothing serious. Anyway, I was in hospital for a couple of days and then came back to college where this girl, who I apparently saved started talking to me nonstop. Moving on, we walked to the station together and then she kissed me and then kissed me on the lips, and she then says thanks again hero. So she changes her relationship status on facebook to married to me so now were going out. I must admit I am not the most good looking guy, I'm fairly skinny. She however is stunningly beutiful. Now I think and everyone else thinks she's only going outwith me because she feel like she ows me something. She ows me nothing but I dont want her to just be going out with me because I saved her.