Our Gemara on Amud Beis discusses various leniencies we grant to a young woman of marriageable age who is also an Aveila. At first the Gemara considers that she is allowed to bathe, but ultimately concludes she may use makeup and style her hair.
It is important to note that the sages had a healthy respect for the natural patterns of behavior and life. I recently heard a Shiur from a rav lambasting the girls’ seminary credo of “Look attractive not attracting”. He claimed while this was a clever saying it was philosophically and morally, nonsense. Nothing more than verbal sophistry. He said, simply put, a woman should not dress in such a way that attracts attention to herself. He said you can call it anything you want, but women are obligated to be modest.
I found his willingness and zeal to confront popular dogmatic statements refreshing, however I think in this case he was wrong. While the rabbis were certainly in favor of modesty, they also clearly recognized the value of a woman looking attractive. In this particular case, they are giving extra emphasis to a young woman who is of marriageable age to the extent that they are waiving certain normal requirements of mourning. But that is so far as mourning is concerned. They aren’t waiving requirements of modesty in general. Obviously, they felt it was appropriate to appear attractive when one needs to find a mate.
However, this is not limited to the sphere of single women of marriageable age. There are other situations in the Gemara where great care is taken so that a woman not appear unattractive to her husband. See for example Shabbos 64b where allowances were made for a woman who is a Niddah to still adorn herself, and Moed Kattan 9b, where it is recognized that even an elderly woman “standing at the edge of the grave” cares to adorn herself and wear makeup. The rabbis had respect for the basic human needs and rhythms of life. Many women enjoy looking attractive, and this is a normal part of life’s pleasures and should not be squelched.
So, while you shouldn’t believe everything they teach you in seminary, it looks like they got this one more or less correct.