Question

Who says the following and why (bold text)?

—Then she hath sworn that she will still live chaste?

—She hath, and in that sparing makes huge waste;
For beauty, starved with her severity,
Cuts beauty off from all posterity.

Answer 1

Romeo thinks that his love is wasting her beauty because she will not "share" her beauty with him.
Romeo is criticizing his love for her vow of celibacy because she is beautiful but "keeps" it in that she will not pass it to her children.
Benvolio is trying to convince Romeo that he is wasting his time on this girl because there are many other beautiful girls.
Benvolio is pointing out to Romeo that the girl he loves is really not that beautiful.

Answer 2

@iambatman

Answer 3

@haleyelizabeth2017