sorry dont want to seem like a nag lol but no amount of human attention ever makes up for another of their own kind, woudl be a bit like us living with an animal we cant really speak the language of end NEVER seeing a person to interact with.
i NEVER keep ferrets alone, even my V.hob lives with others all year round, the only ferret i have alone is a hybrid who has inherited pretty much everything polecat and not a lot of ferret and as polecats are solitary it causes her more distress to be with others but she is exceptional and would not behave that way if she was a ferret.
there is no better sight than two ferrets playing together and if you could see 12 of mine all piled into the same bed or hammock you will see they like to curl up together.
not lecturing, just saying ferrets are sociable.