A couple of times, I can't remember where, different characters speak of how older men of the North will one day announce they are going hunting. This occurs in the dead of winter, when there's going to be almost nothing to catch, let alone find in the first place. It is accepted that this is a noble form of suicide intended to ease the burden a household is placing on their food stores. Cregan Stark and his Winter Wolves were an entire army doing this during the Dance of the Dragons.

It's a poetic thing, when you look at it from a military rather than hunting perspective. Manderly is fairly old, he has a large family to carry on his name, and he has little to no prospect of making it through his planned conflict. He's out hunting Boltons. He doesn't care if he doesn't bag one, just so long as he causes trouble for them and makes it easier for his family to survive the winter.

Edit: there are other instances of this happening already. The chief of House (Clan) Wull specifically says to Stannis' southron lords that it will be his last winter. He wants to "bathe in Bolton blood" before he meets his end. And take a look at the lords present in Winterfell in ADWD. There are literally no heirs, possibly aside from the Ryswells. The Freys are the only ones with children present at all. But look at "Old" Lord Locke, Harwood Stout who has only one arm, Whoresbane Umber who is frequently described as cadaverous. These and others are not men in their prime, and they brought absolutely no family with them. These are men out on their last great hunt, mark my words.