OP has EU citizenship, OP's partner does not. OP was under the impression that their non-EU partner will loose their right to work in the UK.
That's definitely not the case though, and I've replied to OP on the steps to securing a "Settled Status" for their partner.
> The rights and status of EU, EEA and Swiss citizens living in the UK will remain the same until 30 June 2021.
[0]: https://www.gov.uk/settled-status-eu-citizens-families/what-...