In order to understand the rhetorical questions in the sestet of the sonnet "Astrophel and Stella XXXI" by Sir Philip Sidney, it is necessary to understand what has gone before. In the first quatrain, the speaker is noticing how slowly the Moon rises and is musing about whether Cupid has shot arrows of love even out to the Moon ("That busy archer his sharp arrows tries!').
In the second quatrain, which introduces a change in topic and in tone, he concludes that, yes, the Moon is also a sad and lonely lover who is unsuccessful in love ("thou feel'st a lover's case,"). The speaker knows this because his own experience with love is unsuccessful and sad and he recognizes the signs ("I read it in thy looks; thy languish'd grace").
The rhetorical questions follow upon this revelation, that the Moon is also a saddened unsuccessful lover/suitor. The speaker thusly asks if, even in the heavens where the Moon resides, it is considered foolish and unintelligent to be constant and steadfast in one's love for someone, suggesting that the speaker's love is unrequited (unreturned).
The second question is whether in the heavens beautiful ones are as proud as they are on Earth. And finally, the speaker asks if those in the heavens love to be love but nonetheless scorn the ones who love them, while wrongly calling the virtue of constant love "ungratefulness."
The narrator, Astrophil, is suffering from unrequited love and notes how "wan [pale] a face" the moon has as it rises. Astrophil projects his own experience onto the moon, imagining that it must be suffering love pains too. Having established an identity with the moon—"to me, that feel the like, thy state descries"—he proceeds to ask it a series of four questions. They are as follows:
Is constant love deem'd there but want of wit?Are beauties there as proud as here they be?Do they above love to be lov'd, and yetThose lovers scorn whom that love doth possess?Do they call virtue there ungratefulness?