Horror Magic: the Invest spell if Magery is Switchable / ways to un-Invest?

[Plane]

Given that the limit of how many followers you can Invest is based on your Magery, what should be the effect if you effectively have Magery 0 due to switching it off?

At the very least probably not getting character points when they do crit fails, but should it also sever the bond so you don't get CP even after Magery comes back?

Also is there any way to sever the bond other than killing the follower? Like if they get really skilled and stop crit-failing you don't gain as much from them.