She would not accept your proposal

[Tait-ka]

Hi,

Tom: I am going to propose Maria.
Bill: She would not accept your proposal.
Tom: Why do you think so?
Bill: Because she always says she wants to focus on her studies and career first, and she treats you like a friend only.
Tom: But I feel she likes me.
Bill: Liking you as a friend is different - she doesn't want to turn that into a relationship right now.

I created the above dialogue.

Can you please see the bolded red sentence? An English teacher says that here Bill is making an assumption about the future by using "would", though he is speaking in the present. He is assuming that Maria is not going to accept Tom's proposal. If Bill uses "will", there is more chance/certainty that what he is saying will be true. With "would", there is less chance/certainty that what he is saying will be true.
So:
She will not accept your proposal=> More certain
She would not accept your proposal=> Less certain.

Could you please let me know whether the teacher's right?

 

[5jj]

Tom: I am going to propose to Maria.

Note the missing preposition

She will not accept your proposal=> More certain
She would not accept your proposal=> Less certain.

That's roughly right.

 

[Tait-ka]

Hi @5jj.
Can you tell me whether that red sentence of Bill correctly uses "would" (meaning Bill is assuming that she is not going to accept Tom's proposal)?

 

[5jj]

Can you tell me whether that red sentence of Bill correctly uses "would" (meaning Bill is assuming that she is not going to accept Tom's proposal)?

Not necessarily. There is an underlying condition, if you proposed to Maria. This is less certain than the underyling condition of the sentence with 'will', if you propose to Maria.