When my husband had his first A, he told me while on a Thanksgiving get-away, on Thanksgiving Day. After sex. "Oh, by the way, I want a divorce". I cried for about 12 hours straight. On the way home, he asked me "if we could keep this quiet until after Christmas". WTH? Yes, honey, let's play house and pretend everything is wonderful for the next 30 days. Make it 40 and we'll cover New Years. I told him that wasn't going to happen.
IMHO, the reason he wants it hidden is because he knows who is to blame, and they DON'T LIKE BLAME. They feel the guilt, and don't want others looking at them with blame on their face. The Holidays are tough at the best of times. This just compounds the difficulties. My husband left and came home twice between Thanksgiving and Christmas, and several times after that before his head became dislodged from his a$$.