I'm also not so sure that Methodists, if that what Alma Jr and her mother were (we're only assuming this because Ennis says his folks were - past tense) would have been concerned about the divorce Protestant churches have a problem with it because the Anglican Church is founded on the acts of a king who wanted an annulment, not a divorce, and consoidered himself Catholic till the day he died. However, he subsequently divorced another queen (Anne of Cleves), leaving Anglicans with the problem of how to regard divorce - one they're never quite solved, though they've tried to get round it in all sorts of ways - allowing the "innocent" but not the "guilty" part to marry again in church, eg. (One of those times where at least you know what the Cathjolic church stands for since they don't accept divorce and that's that - ish.)
Methodists and the other Protestant groups also have ambivalent attitudes, the problems associated with which which they try to fudge. I imagine as long as Ennis was there merely as Alma Jr's father there would have been no major problem, though divorce was less common in the 60s and being divorced might have made Ennis appear "different".