There are 3 ropes to pull but only one is correct and will release your otter girlfriend. Therefore, there's only 1 bad ending medal.
I think the first rope is always correct. In my first run, I pulled the third rope which was wrong. Then pulled the first one in my second run. I also watched a walkthrough and yup, also the first rope was correct. There are no clues, it's just based on luck when you don't know what I just wrote.