Isn't it an old customary thing with American weddings anyway that the bride's family hosts/pays for the wedding and the groom's family host/pay for the rehearsal dinner (and something else I think---favors for the wedding party? Which used to be an important courtesy item---gloves at least, richer folk might give watches, a nice piece of jewelry, etc.)

She should have hosted the rehearsal-night dinner, is what I'm saying. The LW is letting their shoulds get in the way of realities.