The guy who was conducting the sonar search said it is literally impossible for her to be taken out to sea due to where the river is. If it was closer to the sea maybe.
Look at the other options:
Abducted unconscious - 10 minutes to run to her, knock her out and drag her body away, looking at area this seems extremely unlikely
Abducted conscious - threatened with knife/gun, possible but why do it in broad daylight on a busy path? 10 minutes isn't much time to convince a 45yo without an argument. An attacker would have been seen acting suspiciously.
She ran away - look at her social media, she's besotted with those kids and the dog, the police found no issues at home
Suicide in river - same issues as accidental
Suicide somewhere else - possible, again, 10 minutes to get out the area at the right exit with no witnesses. Zero evidence she was unhappy.
You're left with two realistic options, the river or someone with a threatening weapon. The abductor would have to be living close, the farm with caravans is the only option, I would assume the police looked there. Again, the river is the most likely option as the dog would have been found at the farm.