Restrict access to just one group at the same time

Problem/Motivation

I have a website, where one particular user (group member) can be added to multiple groups. It means that they can have access to content of multiple groups at the same moment. It can be confusing in some use cases. I would like to restrict access to content in that way, that user can use CRUD operation only to one specific group (and its related content) at the same time.

Steps to reproduce

Proposed resolution

Maybe it could work in that way, that user could swicth to particular group using some element
(for example selectbox). The selected group ID would be stored in PHP session and access to all content would be checked by this stored value.

User interface changes

Some switcher to select a group.

I am willing to work on this issue, if such functionality is not done yet and others think, that it can be useful, too.