What's wrong with me?

I'm not sure what is going on in my heart and mind right now and admittedly this is very odd for me; but for some reason I just can't seem to get into the holiday spirit. Is it wrong of me not to want to decorate, stress, shop and yes; unfortunately just keep to myself this Christmas? I really do not understand the reason for this sudden "change" but could it simply be my peri-menopause and my hormone's are screaming "DON'T COOPERATE WITH ANYTHING!" ?
I've thought about, analyzed and re-analyzed reasons for this about-face, but still can't pinpoint any one certain thing. I lost my grandpa this year and am still so frustrated that I wasn't there for him or there to say goodbye. It was so unexpected. But I've always had the mind to practice what I preach.... (which would lead to an entirely different article so I'll just leave it at that). Who knows? Perhaps it's because Christmas has become such a commercialized industry which has led society completely astray from it's true meaning... We shop, we stress over getting the house decorated, the cards mailed out, the gifts wrapped, the food prepared, yadda yadda yadda. You catch my drift.
Maybe I really am just growing older and growing tired. It is very disconcerting for me as I've always been the bubbly, happy "cheerleader", but heck! Not so much anymore....