Not stupid at all!! Here's how you get ending 3 and 4 (I'll put it under the cut in case people want to figure out it out on their own :)):
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After the Stage 2 mark, choose all 4 options that show your interest in finding out more about Chao, including kissing him. Choose:
1. Dig deeper
2. They want to tell you something
3. There's something more
4. Kiss him
It'll automatically lead you to the branch leading to ending 3 and 4 :) Thank you so so much for playing LD! I hope you enjoy these endings as well <3