"But why should you think of it?
Why, the young fellow has only been here four or five days!" "That is quite long enough for him to see that Mary is a charming girl," Mrs.Lindsay said.

"He has seen very little of ladies; and he is, no doubt, struck with the idea that she is an extremely nice girl.

I don't say that he is in love with her, yet; but quite enough, perhaps, to foresee that, ere long, he will feel more ardent than he does at present; and that it is the only arrangement possible, since we are determined to turn out for him.
"Now mind, Peter, you do not throw out the slightest hint, either to him or to her, that such a solution has ever occurred to us.

It might spoil everything.

It would make Mary shy with him, and might cause him to be awkward.