You do not have to fall or roll. Nope. Not even the safe soft ones in my videos for falling for non-martial artists. Not. At. All. In fact, you don't have to throw your partner either, if that's hard. Whichever role, just go to balance-taking. That's the important part anyhow, and learning to have control of uke to that point and stop is great.You do not have to do every technique that a given class is covering. It's ok to sit out.
I injured my AC joint when a sempai accidentally disconnected from me during high fall practice. Sensei told me these exact words of wisdom! I was back training after 1 month. A bit gun shy I must admit.