Albert Barnes on 1 Peter 3:2

While they behold your chaste conversation. Your pure conduct. The word chaste here (αγνην) refers to purity of conduct in all respects, and not merely to chastity properly so called. It includes that, but it also embraces much more. The conduct of the wife is to be in all respects pure; and this is to be the grand instrumentality in the conversion of her husband. A wife may be strictly chaste, and yet there may be many other things in her conduct and temper which would mar the beauty of her piety, and prevent any happy influence on the mind of her husband.

Coupled with fear. The word fear, in this place, may refer either to the fear of God, or to a proper respect and reverence for their husbands, Eph 5:33. The trait of character which is referred to is that of proper respect and reverence in all the relations which she sustained, as opposed to a trifling and frivolous mind. Leighton suggests that the word fear here relates particularly to the other duty enjoined--that of chaste conversation--"fearing the least stain of chastity, or the very appearance of anything not suiting with it. It is a delicate, timorous grace, afraid of the least air, or shadow of anything that hath but a resemblance of wronging it, in carriage, or speech, or apparel."

(+) "conversation" "behaviour" (++) "fear" "reverence"