"31 or thereabouts" is an ideal age for a woman - mature but not middle-aged. I was "thereabouts" for several years.
A father and son in one of my lines each married in mid 20s to spouses a decade older. One was a widow. Both wives outlived their husbands.
As Ann's brother was aged around 40 and unmarried at the time of her marriage perhaps Richard had hopes of his potential children inheriting.
I’m still waiting to become “middle aged” though I’ll start getting my state pension in a couple of years or so
. Interesting point about her unmarried brother. If that was Richard’ plan, it certainly backfired. Ann gave her deceased husband’s estate to her nephews and nieces, though the children of the elderly brother got very little, presumably because he had been the eldest son of Ann’s father and had therefore inherited most of that estate. (I think there is probably some sort of kinship link between Ann and her husband's family, though I can’t quite nail it).
