このDVD面白かったら、よかったら見てみない。


> このDVD面白かったら、よかったら見てみない。
>
> a-ありがとう、見てみるね  
>  b-ありがとう、見てみようね

Can someone explain why a is correct and b is incorrect? As far as I know,
when you use ない it is 誘い・提案 - invitation, suggestion for 一緒にする

so if its a invitation for 'us' I assumed it would be b, where よう means sure
lets watch it together.




"見てみない?" does not necessary mean "let's see/watch it together". Besides, the
second person said ありがとう, which indicates the first person **lent** the DVD to
the second person. If this scene were of two people in the same room
discussing what to watch now, saying ありがとう would be unnatural.




"見てみない?" does not necessary mean "let's see/watch it together". Besides, the
second person said ありがとう, which indicates the first person **lent** the DVD to
the second person. If this scene were of two people in the same room
discussing what to watch now, saying ありがとう would be unnatural.

