A couple years ago, one of my first indications that something was systemically wrong with the organization was when a friend of mine told me about his cousin that had just gotten DF'd. His cousin had recently gotten married, but it came out that they'd had sex before hand. He got DF'd but his new bride only got reproved. My friend said that this was because the elders in his congregation had a "three strike rule" and he'd gotten in trouble with other girls in the past (many years prior).
My first thought was that Jesus reproved his disciples for daring to limit forgiveness to 7 times, but these assholes are taking someone who's clearly not going to re-offend (being that he actually married this girl) and they're giving him the boot because they can't bring themselves to forgive a measly 3 times?
Same thing with DFing people just because they get in trouble twice within some arbitrary, man-made time window. If they're repentant, they should continue to forgive them indefinitely in keeping with Jesus' statements. Maybe some good will come of it, though. Maybe some of those who are DF'd because of rules like this will wake up as a result and won't remain in a mental prison.