May a woman (who got married 4 months ago) shave and tweeze during the 3 weeks? Thank you.
It is permitted for a woman to undergo cosmetic treatment (shaving and tweezing) during the Three Weeks.
Sources: The question of a haircut for women in the Three Weeks is disputed among authorities. Some maintain that it is permitted for women to take haircuts even during the week of Tisha Be’Av (see Panim Meiros, vol. 2, no. 37), and this is the custom for Sephardic women (see Chazon Ovadyah, Taanios p. 163; see Or Le-Tzion vol. 3, chap. 27, no. 3, who writes that although it is permitted for women to take haircuts throughout the Three Weeks, it is preferable to defer the haircut until after Tishah Be’Av).
For Ashkenazim, some authorities rule that women must be stringent with regard to haircuts from Rosh Chodesh Av (Noda Biyehudah YD 99; Pri Megadim, Mishbetzos Zahav 551:13; Kaf Hachaim 551:47), while Mishnah Berurah (551:79; see also Mishbetzos Zahav 551:3, and Derech Hachaim p. 169) writes that there is no distinction between women and men, and haircuts are prohibited for all (Ashkenazim). In this matter, one should act stringently in accordance with the ruling of Mishnah Berurah.
However, Mishnah Berurah (ibid.) writes that for hair growing on temples a woman may be lenient, and Halichos Shlomo (p. 414) states that the same applies to other forms of cosmetic treatments (eyebrows).