Exactly, FD would probably be the last person JD's friends or family would call if they were concerned about her whereabouts. They were estranged. He had threatened her. She was afraid for her life. He was not allowed to contact their children or speak with them or see them without court appointed supervision.
The very next week after 2 long years in divorce court, FD was due to be in divorce court to finally cough up the financial information that he had been refusing to provide in the previous court proceedings, that would probably show what a sham his life was, and what a scammer and fraud he was.
So FD would be the last person for family or friends to check in with, IMO. Now LE, once she was reported missing, that would be another thing entirely, IMO. They were probably already on alert to be on the lookout for FD to do something terrible to his estranged wife, and jumped right on it that same day, which FD was not expecting, hence the early evening dumping of evidence that had JD's blood on it and / or the disposing of her body early the next morning at his nearby NC property.
'Be prepared' isn't just the Boy Scout motto; LE was ready to snap to as soon as they were alerted, and so were JD's friends and family. I've heard of some people on the periphery in DV situations to call local police stations and just tell them, 'hey, you should be aware that if ___ every goes missing, you should look at ____ right away for these reasons'. Or LE could have already been on top of the situation 'through the grapevine' -- NC is not that big of a town.
JMO, it's very tragic that all their vigilance and quick reaction time couldn't save JD from a soulless maniac who took her life, but it was very heroic on her part to fight back (which I assume she did when attacked in the garage due to the blood evidence LE found), and do everything she could to protect her children, to have a plan in place and regular check-ins with friends and family, etc. Way to go, JD, friends, and family. Very admirable, and a saving grace for your family involved unwittingly with such a monster. I also think something big is about to break in the case as LE finishes running to ground the 1000+ tips, dozens of video surveillance, and processing evidence from a month of combing through MIRA. All JMO.