Q. Can one attend a bridal shower (for a non-frum soon-to-be relative) during the 9 days?

A. In principle, one may make and attend a vort or a shiduchim ceremony even during the Nine Days, if done without a Seudah (banquet), music and dancing. This may be done immediately to pre-empt loosing the shidach to someone else (Shulchan Aruch O.H. 551: 2). However, Horav Shlomo Millers Shlit”a opinion is that a bridal shower does not concord with the mourning spirit of the Nine Days and should be avoided. Especially when gifts that may invoke the need of blessing “sheheyanu” (which we do not recite during this period) may be involved.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a