I think Edward's silence is required for this brilliant "he loves me! he loves me not" to work, and when Edward does finally turn hastily and speak, it's perhaps another "he loves me!" petal that only increases the uncertainty for everyone...
Notice how we learn of Edward's "regard" for Elinor (the italics are mine) -
JA has Mrs. Dashwood build the suspense, starting in Ch 3:
she feels "the persuasion of his regard for Elinor"
"No sooner did she perceive any symptom of love in his behaviour to Elinor, than she considered their serious attachment as certain,"
Elinor "knew that what Marianne and her mother conjectured one moment, they believed the next"
Even Fanny notices
The relationship was "perceived by his sister"
JA uses the women's feelings, assumptions, & wishes to suggest and build up Edward's side of the relationship; never is there any direct evidence or declaration from Edward himself. We see the crescendo of feelings (of Mrs. Dashwood & Marianne) right up to the "Esteem him! Like him!" exchange in Ch 4.
Then the "relationship" balloon begins to deflate with Elinor's words of reason, and it is her feelings almost squash it entirely.
Elinor requires more than a feeling to convince her:
"She believed the regard to be mutual; but she required greater certainty of it to make Marianne's conviction of their attachment agreeable to her."
"I am by no means assured of his regard for me."
The closest to evidence we get is Elinor’s observation of Edward, and her interpretation of his feelings:
"There was, at times, a want of spirits about him, which, if it did not denote indifference, spoke a something almost as unpromising. A doubt of her regard, supposing him to feel it, need not give him more than inquietude. It would not be likely to produce that dejection of mind which frequently attended him...(Elinor suspects that EF is hesitant for fear that his mother will not approve the match)... Nay, the longer they were together, the more doubtful seemed the nature of his regard; and sometimes, for a few painful minutes, she believed it to be no more than friendship."
With Elinor's uncertainty, JA puts the reader on her guard, as well, about the possibility of an Edward/Elinor relationship.