Women like symmetry. Order another one.
Show her pictures of larger more invasive subs that you could have gotten.
Show her pictures of hotter younger women that you could have gotten.
Don't shave for a few days and cut the sleeves off of a few of your shirts. Break wind at every opportunity. Remind her that you're a man and she's dang lucky to have you, that subwoofer, and a house to put it all in.