It's a very difficult problem and I don't blame anyone for being scared. Expecting people who live with shielded people to return to work now seems illogical to me. How can you be shielded when your own family is coming in and out? The shielding rule should cover everyone in the household.
It is true, of course, that we will have to come out of isolation eventually. However, nothing really has changed. We have probably helped the NHS to cope, because of the lockdown, but the virus is as active as ever and medical treatment is still very limited in what it can do. Vulnerable people should be protected until something changes - a vaccine, a treatment or, at the very least, a comprehensive system to test and trace. That should have been done at the beginning...
Sorry, I know this doesn't help to solve the problem. There is no perfect answer. All the advice here about hygiene is very sensible, and you might have to think seriously about dividing your home temporarily into his and hers zones. Not an easy problem to solve.