Do you think it’s wrong to say yes to an engagement proposal because they proposed in public?

Okay so say a man proposes to a woman in a very public place in front of a lot of people, including the man’s family. The woman doesn’t think their relationship is ready for marriage or engagement even and she isn’t quite ready. But she doesn’t want to embarrass him in front of everyone. Would it be wrong for her to calmly say yes, then tell the truth when in private?