Explain "its frothy sweet" referred to in stanza 2 of the poem

Which is best evidence that mary is beginning to change

"and these i address to all females that would be married, or are already so; not that i suppose their sex more faulty than the other, and most to want advice, for i assure [women], upon my honour, i believe the quite contrary; but the reason is, because i esteem them better disposed to receive and practice it, and therefore am willing to begin, where i may promise myself the best success." this statement from franklin's "rules and maxims for promoting matrimonial happiness" best demonstrates his use of criticism to argue his point his use of common sense to appeal to women his use of flattery to gain women's attention his use of facts to prove his point

This is a set of words that begins with a preposition.